Deliberate mistake: When Frenzy attacks Sam, the teenager wears straight leg jeans with a narrow leg opening (not boot cut) and thick-soled Nikes, seen in numerous shots, as he kicks at the Decepticon. After the cut to Mikaela (who finds the reciprocating saw), during which Frenzy has already pulled off the bottom of Sam's jeans, Sam continues to kick and scream just before he gets up and runs. Problem is Sam still wears both thick-soled Nikes, neither of which slipped off as Frenzy maniacally pulled the jeans, with narrow leg openings, from his kicking legs/feet. Impossible even in the best of circumstances.
Deliberate mistake: During the scene where Carlos and L.J. are searching the motel, L.J. sees a zombie which turns out to be a reflection in a wall-length mirror. L.J. shoots, breaking the mirror and realizing his mistake. But, if he had been standing in front of the mirror as shown, he should have seen his own reflection standing there as well. This was done as an homage to a similar encounter in the original game. (00:24:20)
Suggested correction: There are two mirrors. One of which is at angle and reflecting an area that LJ wasn't in. Hence why he turns around about 45° and gets attacked by the woman. As such, he's not going to see his reflection.
Deliberate mistake: Bender goes back in time to two minutes before Fry came back to the past. But if you time it, it was actually only 1 minute and 42 seconds.