When John is teaching his class, he receives a phone call, a student raises her hand and calls him Mr. Savage. However, earlier in the film it is learned that he has a PhD, therefore she should have referred to him as Dr. Savage.
When Larry drives to Buffalo to pick-up Wendy for the day, he brings his dog, the cat, and the house-plant. They all leave together and when they end up in the hotel room, the dog is gone. Then when Larry drops off Wendy back at John's house, she has her cat and house-plant but Larry's dog is still missing.
Wendy and Kasia agree to be at the airport at 7AM. In the next scene, we see them eating breakfast and it is light outside. It would not be light in the morning in the NE in the winter. This error is repeated when they arrive at the airport.
Lenny Savage's girlfriend's children claim a prenup-like document prevents Mr. Savage from common law marriage claims on the Arizona home he has been living in for 20 years, however, the state of Arizona does not recognize common law marriage.