When the honeymoon inn emcee is announcing the newlyweds, the first word he is heard saying is "Folks," but his lips don't start moving until the second word, "to." In fact, he ends the same sentence in the repeated words "folks," so this was probably a mistakenly repeated word when the monologue was re-recorded for the film's audio.
The first customer in the butcher shop is shown being handed her purchased material, then leaving the shop. In the montage that follows this scene, she is again shown when Charlie says "Mom, help! It was an accident in shop."
When e first see the honeymoon hotel (in reality Dunsmuir House) there is a tower that is not there in on the real hotel. Regardless of that, in the second shot of the hotel, the tower is missing. Also, there are no mountains/cliffs in the background.
Alcatraz Island Ranger Vicky states that many of the Park Rangers are former guards of Alcatraz, including himself. The prison closed on 21 March 1963, 30 years prior to this movie. This would have made Vicky a teenager at best when the prison closed, and too young to be employed as a guard. However, Ranger Vicky is most likely just telling a tall tale.
Anthony LaPaglia (Tony) noticeably corpses (breaking character by laughing) during Stuart's rant about Colonel Sanders. He almost corpses several times earlier in the scene but manages to recover, a couple of times using his beer bottle to hide his mouth.
The goof items below may give away important plot points.
While Rose is hacking away at the roof, Charlie keeps removing the hand she's aiming for. After several chops, Rose chops into the roofline, just between Charlie's fingers. But there are no other chop marks to be seen along the eave.
The marks that Tony leaves when trying to break down the door at Poet's Corner disappear. In fact, Tony smashes the doorknob when he kicks the door and when the marks go away, there is a shiny new one.