Factual error: In the deli, which is obviously not a kosher one since one of the items on the menu is "shrimp salad," a Chassidic Jew can be seen eating there. This would not happen in real life, as Chassidic Jews keep the laws of kashrus and would not be eating in a non-kosher restaurant.
Suggested correction: You seem to be referring to the deli in Jack's delirious dream when he wrote the deli into existence. Being a New York delicatessen, he would have simply written about the Jewish person being there. Of course, the Jewish person seen isn't real, he's part of the dream. The real deli at the end doesn't have a Chassidic Jew in it.
Character mistake: One of Jack's fellow producers starts choking on a pickle, the other knows this yet says it's a sandwich she's choking on.
Continuity mistake: Janet goes back and forth from needing to wear glasses to seeing perfectly fine.
Suggested correction: Janet wasn't real. She was a character in Jack's delirious dream. In Jack's dream, he was saying the things Janet was doing was written by Federman, and sometimes he controlled the scene. Not to mention the fact that some people only need glasses to see certain things and can see without them in other incidents or she was wearing contacts.
Factual error: A football game is shown playing on TV at one point. Impossible as the movie is taking place in spring - football games, both college and the NFL, are played in the fall/winter.
Suggested correction: This is during Jack's delirious dream and he wrote it that way to distract Carter who was waiting for the cable repair man. It wasn't something that was meant to be happening in real life.
Other mistake: Jack gets hit in the face by a car trunk but when he wakes up later there's no cuts or bruises on him.
