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.
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.
Jon Savage drives his Polish girlfriend to the airport at 6:30 AM, in broad daylight. But in November in Buffalo, it would be pitch dark at this hour (even on November 1, sunrise isn't until 7:46).
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.
When Wendy plugs in the lava lamp, it immediately starts flowing. Lava lamps typically take longer to start movement.
On an airplane, people in wheelchairs board first not last, and they sit in the front seats.
Wendy would not have been startled to find Kasia in the living room. Wendy would have seen and smelled Kasia's cigarette before getting to the room.