Try to follow my possibly goofy logical thinking. Morgan is 26 according to his own mother, and Chuck was a senior at Stanford in 2002 which would make him about 28 or even 29 today, same as Sarah. In Chuck Vs the Best Friend it starts out in 1992, 17 years ago making Morgan 9 at the time. Morgan is knocked down by a little girl (who's bigger than him by the way) at the Elizabeth Stanton Middle school. Middle schools vary in grades from 6-8 and 7-9 depending, but lets give the benefit of the doubt and say grades 6-8 the avg ages of kids are 11 & 12, not 9 or 10 as Morgan. To make Morgan's age closer to correct the writers say as the scene switches to today than it's 15 years later not the 17 it really is. In Vs the Best Friend Chuck tells Sarah that he and Morgan have been best friends since kindergarten. Now we know Chuck has a high IQ and Morgan is about average at best. Meaning Chuck couldn't have been held back in kindergarten and Morgan could not have gotten in at age 3 or 4.
In real life Zachary Levi is 28, Yvonne is 26 and Jashua Gomez is 33.
Conclusion; The writers write pretty well, however they can't do math at all. Just as likely is that I've seen way too many episodes of Psych and it has got me conditioned to noticing way more detail than I should be seeing, since it's just a TV show and not a murder investigation, and need to just let it got.
Does anyone else notice these things or should I go back into full time therapy? roflmao