- This is a rare case where fridge logic delayed and altered a film after it was believed finished. In the cut of the movie screened for critics (and also the director's cut released on DVD), Stuart is Leopold's great great grandson. Critics noticed a problem with this plot point that the director hadn't. When Kate travels back in time with Leopold, she becomes (and always was) Stuart's great great grandmother. This means Stuart had a long (and apparently sexual) relationship with a relative. The plot point was edited out to avoid this problem which caused the film to miss its announced release date.
- Because the inventor of the elevator is brought to modern times using time travel, all elevators start malfunctioning and eventually disappear. One of the characters explicitly brings up that if he is not returned quickly, people will vanish that would have been his descendants. Presumably the same thing would happen to them as did happen to the elevators-first they would all start gaining more severe medical problems until eventually they all died and vanished.
- How well is Kate going to get along stuck in the 1800s? Her job is completely impossible there, so she has no way to make a living, which leaves her dependent on Leopold (in a time without much in the way of women's rights), and if their relationship should go bad, she's up the creek without a paddle.
- A site discussing how the ending of the movie was depressing lays these facts down:
The media will spin the whole thing to make it sound like Kate was psycho and her company actually attempted to hire her. Because of this, they'll suffer a severe backlash economically.Nurse Gretchen is going to either have her medical license stripped from her or jailed for willingly letting a believed-to-be-insane patient run back out into polite society, therefore endangering both himself and others.Leopold is MIA and, from the perspective of the NYPD if you consider all the evidence that site lays out, Leopold looks like a monster who conspired with ex-boyfriend Stuart (the aforesaid mental patient) to drive an emotionally and mentally unstabled woman to jump off of Brooklyn Bridge.Charlie is going to have a hell of a time trying to get a job now that people know he was related to a girl who seemingly killed herself and friends with two men who seemingly drove her to kill herself.