Plot hole: The movie is based in 1986 after the group time travels from 2010. That makes it a 24 year trip back in time. It is stated that Jacob is 20 years old. That is an error as this would make him roughly around 23 or 24 if he was conceived in 1986, which we saw near the end of the movie.
Suggested correction: This mistake has already been corrected. Cusack could have simply generalized his age when he mentioned it, probably not remembering his real age at the moment.
Plot hole: In the scene when the guys bet on the outcome of the football game, their prediction is proven wrong when the vomit covered squirrel from the earlier scene runs onto the field and disrupts John Elway's pass. The movie takes place in Colorado, but the AFC Championship game featuring "The Drive" was played in Cleveland, OH. That's a lot of distance for a squirrel to travel in a couple hours.
Suggested correction: The movie is a comedy. Sure it's unlikely for a squirrel to travel that distance in the given time, but so is a time machine in the form of a hot tub. The scene is there to demonstrate the effects of altering the future, not to prove how fast a squirrel can be. In a comedy, this is exactly the kind of liberties one might expect from a scriptwriter.
