* Mickey Smith or someone from Pete's World's Torchwood will save Sarah Jane, Ianto and Gwen from the Daleks.
* The Doctor's regeneration is misleading: remember what happened with Jenny? She was shot but didn´t regenerate. Instead she recovered (see The Doctor's Daughter).
* The Doctor's name will be revealed, or at least there will be a clue, since his name "is hidden under the Cascade of Medusa herself" (see The Fires of Pompeii).
* The 27 planets are part of a machine that affects time and space. That's why Rose Tyler can travel between paralel world's, and why the TARDIS's Cloister Bell was heard in Turn Left. Davros is planning to use that machine to destroy reality (see above). Rose Tyler has been moving between worlds before all 27 planets were assembled.
* Since The Doctor didn´t obey the demands of the Shadow Proclamation, it's possible that they could show up in order to arrest him. Unlikely, as the 27 planets were 1 second out of phase with the rest of the Universe, and the TARDIS barely made it through to the Medusa Cascade, so how could the Shadow Procloation make it there?
* The Doctor's perceived regeneration is actually a disguised Dalek transmat, which forms part of a plot by Davros to bring the Doctor to the Crucible as part of his wider plans, whilst leaving a genetically-engineered impostor aboard the TARDIS. (Another clue that the Doctor may not regenerate yet is the fact that River Song recognises the 10th Doctor, indicating that he meets her before he regenerates. Yet another, more conclusive clue, is that DT is appearing in all four specials in 2009: However the 'specials' could be an impressive misdirection to cover the fact of DT leaving the show in 2009 and there really will be a full series in 2009).
* There are rumors that Harriet Jones is imprisoned,instead of exterminated as it appeared. However, this is unlikely. Actually this is possible, as we know Sarah Jane will survive, why not Harriet Jones, perhaps the Harriet Jones to Dalek rumour is still true, however she doesn't do it willingly. RTD said that a female we all know very well will die. This is likely to have been Harriet Jones, as everytime she introduces herself, the response is "Yes, we know who you are" including the Daleks. Harriet Jones is not a 'faithful companion' as the prophecy predicted as the doctor was deliberately responsible for her downfall as P.M. Besides, Caan's mentioning of the companion's death is after Harriet is attacked by the Daleks. We know from the static the others received, that Jones' computer was destroyed. This does not tell us anything about what happened to her.
* Harriet Jones escaped just before being exterminated via teleport. After Rose teleports away from the Noble's house, Wilf and Sylvia's eyes widen as if someone else took Rose's place. Since we didn't see her exterminated, she used technology from the Copper Foundation to teleport away and the teleport locked onto the teleport signal which Rose used and allowed Harriet to land in the Noble Home. However this is unlikely as Harriet's words to Jack do not indicate that she planned to survive her encounter with the Daleks. She also seems to accept her fate. But she could have said this as a red herring to return using her faked death as a cover in order to bring down the Daleks later on.
* Gallifrey is restored. Every reference to the loss of Gallifrey is that it was destroyed (or "burned"), not missing as the other planets are. In addition, all 27 missing planets were identified at the Shadow Proclamation (presumably - three of them were speculations of the Doctor's behalf). However, it could be restored like Davros. Why would Davros want to restore Gallifrey?
* Rose dies. Unlikely, as her farewell to the Doctor and Donna has been filmed showing them at Bad Wolf Bay.
* Donna dies. This had been foreshadowed in Silence in the Library/Forest of the Dead, although Donna did already "die" in Turn Left. But then there was the "Sorry for your loss" line in The Stolen Earth, this could be Donna's memory loss.
* Martha dies. Possible as the weapon she has (The Osterhagen key) is rumoured to be a suicide weapon.
* The TARDIS is destroyed or sacrifices itself. Dalek Caan's insane rantings of "prophecy" states that the Doctor's "most faithful companion" would die. This would seem to be the TARDIS, as the TARDIS is indeed a living organism. Possibly supported by video of the TARDIS in flames flying into an "exhaust port" on a fortified moon with only Donna aboard in the Official BBC Trailer for Journey's End Unlikely as pictures on the internet indicate that the TARDIS is in the Christmas special, as well as the Proms special. And if the TARDIS is gone then it's the end of Doctor Who itself. Not necessarily there were more TARDISes before the war maybe Davros captured one. River Song's Diary is styled in the same way as the TARDIS, meaning she must of seen it in the future when they do meet, so if it is destroyed it is somehow restore before their meeting. Also, if the Master escaped the Time War using a TARDIS it may still be in existence.
* The Osterhagen key is either a reset button or a suicide weapon. Also, why would Harriet Jones of all people be opposed to using a reset button? Is it possible that it may be linked to the TARDIS? UNIT know what the TARDIS is. Maybe it allows the stable use of a Paradox machine to be used to Earth's advantage. I know it sounds kind of weird, since Harriet Jone apposed it so much. But it may have been given to Martha as she has been inside the TARDIS. Is this Possible? But if the key were supposed to be used in the TARDIS, then why did the General tell Martha to use it if she didn't find the Doctor? If she couldn't find the Doctor, she wouldn't be able to find the TARDIS either.
* Assuming the ambiguous theories of a 'Botched Regeneration' are plausible, we could be seeing an early version of the Valeyard. In The Trial Of A Time Lord, the Valeyard is seen as an incarnation of the potentially evil side of the Doctor between the twelfth and thirteenth regenerations. Though a couple of regenerations early, the "Osterhagen key" roughly translates as 'graveyard' or 'boneyard' (insults that the Sixth Doctor used against the Valeyard in 'The Trial of a Time Lord').
* K-9 makes an appearance. Likely as we know Sarah Jane Smith survives, and K-9 could save her.
* The doctor's hand is still in the jar, and is still bubbling, as we were pointedly reminded in a shot near the start of the previous episode. This could prevent him changing form, or affect the regeneration in some fashion.
* Sylvester McCoy to make a surprise reappearance... He was interviewed as part of Doctor Who Confidential for "The Stolen Earth" in his seventh Doctor costume, whereas Peter Davison was interviewed in "Civilian" clothing, rather than his cricket gear of the fifth Doctor. - perhaps an unsubtle hint relating to a botched/inverted regeneration. We've never seen the Doctor executed by a Dalek before (or have we?), perhaps he could go back a few incarnations? Sylvester McCoy wasn't wearing any version of his 7th Doctor costume in Doctor Who Confidential, although his hat is possibly the same one (as it originally belonged to him). The block writing used for the "to be continued" at the end credits is reminiscent of Sylvester McCoy era.
* Dalek Caan in the previous episode talks of the coming Doctor as the "threefold man". This could give us a clue. We may well have three doctors in this episode. Perhaps this could include the Doctor's Daughter; Jenny, as she is in effect a clone of the Doctor, and therefore a part of The Doctor himself. (She is not a clone of the Doctor. She is his daughter. Granted, a daughter made using only his DNA, but she will still have different genes to him to due to processes relating to reproduction which are too complicated to go into here.)
* Dalek Caan's insane rantings of "prophecy" states that the Doctor's "most faithful companion" would die. This would seem to be Capt. Jack Harkness as he has been there for 3 out of 4 final stories, but can also die as often as RTD requires.Dalek Caan's prophecy-Isn't Sarah-Jane the most loyal as she did wait all those years to see him again?. No Jack waited over 100 years to meet the right Doctor at the right time, meaning that he out of all the companions is also the most likely to know about future Doctors. Jack spoke about the regeneration process but he was not present on screen for the last regeneration. He has the best understanding of time and may well have traveled with a future Doctor, like River Song, just not talked about it.It could be Donna as she did spend a lot of time and effort looking for him, or even Rose she did cross an entire universe to find him. Rose also said to Donna in Turn Left that she is the "most important Human in all creation" as the Doctor owes his life to her and it would seem she is the most important at the moment. It is unlikely to be Captain Jack as it has been revealed that Captain Jack is the Doctors old friend Face of Boe which we seen die in another episode.(Note Captain Jack is RUMORED to be "the real" Face of Boe, as this has yet to be confirmed.

* The 'most faithful' companion who will die has to be K9: Dogs are always 'most faithful'.(K9 can't be one to die since robots can't die, their not even alive and even if he did get destroyed it would be insignificant since he can be replaced like in School Reunion)
* Again we're told in the previous episode that there's something on Donna's back - after the events of Turn Left (and also long before, in Planet of the Ood). This gives a means to do a "reset" as the entire season could itself be an aberrant time line being ridden by another time beetle. - Though hopefully not, as that's almost as bad a writing as "You mean it was all a dream?" The Shadow Proclamation said there WAS something on her back. The Time Beetle is dead and everything that's happened is happening in the true reality.

* In The Stolen Earth when Donna is sitting on the stairs of the Shadow Proclamation she is seen wearing a large black ring, very possibly the same ring that was the Master's. Although it is unlikely he will appear, it may have something to do with the fact that it will be Donna's last episode. The Master's ring was VERY different to the one Donna was wearing. The Master's was green, whereas Donna's was black.
* The Doctor will regenerate, however the 1 second lapse in the Medusa Cascade will reset his regeneration, giving the Doctor(and us) an insight into what (or who) his next form will be. Unlikely, as a regeneration must fully finish or be botched. Also Unlikely, as it is known DT will return in 2010 as the Doctor. Really? That's still not been confirmed. Yes it has. David Tennant has been confirmed for the 2009 specials not the 2010 series. It sounds like the original claim of 2010 was an honest date error about the specials rather than belief that DT is officially back for 2010 which has not yet been confirmed (either way)

* When Donna is sitting on the stairs, there is a drumming sound, right before the Shadow Proclamation Woman talks to her about becoming something new. She then wipes her eyes, showing off a very large black ring (which is not new; it has been on Donna's hand in almost every episode). As well, when the Sub Wave network starts, there is a tone similar to that used by the Master's Archangel Network in the Series 3 finale, all possible hints at Donna having some level of involvement with The Master. The drumming sound when Donna is on the stairs is a heartbeat, possible a slight echoed beat of two hearts, but it's not the same as the Master's beat.
* As Sarah Jane is about to be exterminated Mickey suddenly teleports and saves her while Jackie does the same with Torchwood

* Davros claims reality is to be destroyed... and in Turn Left The Doctor mentions realities bending around Donna... perhaps this could lead to her exit... Perhaps Donna is still in "The Library"? This would give an explanation to Donna's face on the node in The Library. unlikely, as anyone who was saved into the computer was able to have their faces on those nodes. Donna's lover inside the computer had his face for her outside on a node, but he was also restored. Also, if this was true then everyone else would still be in the library, which we know is false. The only remaining people inside the library computer are River Song and her companions and C.A.L. No-one else needs to be in the library if Donna has been "saved"

* The planet where the Bees' are heading is called by the Doctor "Miasimia Goria". This is the same planet Rani used for experiments in "The Mark of the Rani".

* Donna is actuatly romana and used the ring on her hand as a camelion arch to stop her fighting in the time war and then regenerates into river song

* The events/characters of the "Trial of a Time Lord" may factor in--maybe the Valeyard. The Doctor mentioned in "The Stolen Earth" that the earth had been moved once before, and the only time we've seen that happen was in "Trial of a Time Lord."

* In the first episode of the series Donna states that she'd been searching for the Doctor for a while. This may have lead her to the Masters dead body at the end of series 3 making her the woman that found his ring. If Donna is the companion that dies in this episode then the Doctor may find the ring in her pocket and keep it aboard the TARDIS until some time in the future in which it will play a part in the Master's ressurection in a future series. This theory is somewhat supported by the fact that Donna's computer played the tune of the Master's drumbeat (or a tune very similar) when the subwave network started, showing a clear link between the 2 characters.
* Donna has to pilot the TARDIS into the heart of the Death Star through it exhaust port and reach the Death Star's main reactor and fire concussion missiles and proton torpedoes at it, causing it to collapse. The Ostenhagen Key is the secret plans to the space station, smuggled too the Rebel forces by Martha to help the find a weakness. Oh, the Doctor is going to turn into a Wookie. I think RTD might have been given a certain Trilogy DVD boxset for christmas last year after seeing the latest trailer...