Continuity mistake: When Wanda and her husband drops off her wolf pups at the kids club, when they are outside her teeth are different shapes and sizes, but when they zoom in they are straight just like her husband's. (00:27:10)
Continuity mistake: During the Macarena scene, when Drac's cape dances, Johnny's DJ disappears.
Continuity mistake: As the monsters are walking down a hallway towards the dance party, Frankenstein has his lobster claw hands and he's walking with them swinging happily out and in front of him with stride. But in the next shot suddenly his arms are down calmly by his side as he walks more casually. (01:07:50)
Continuity mistake: Dracula pushes his daughter Mavis out of the attic room when he's on the phone with a witch and shuts the door behind her. Mavis is shown standing there in a shocked expression with her back to the door. But in the next jump cut, she's suddenly turned 90° and has her hand on the door handle, frowning. (00:11:55)
Continuity mistake: The beginning of the movie shows the year as 1897. Dracula and his group of dudes are on a train going on what seems to be a vacation. Once Van Helsing attempts to kill the monster gang, a series of other previous failed attempts to murder Dracula play out. At the end of the flashback Dracula says it would be great if there was a place for monsters to go, possibly a hotel. The problem is Mavis was born in 1894, and in the first instalment we learned the hotel was being already being constructed when Mavis was a baby three years earlier.
Suggested correction: He had actually said something about being able to go and maybe even get married. He obviously wasn't planning on having weddings at the currently under construction hotel.
He had already been married by this point and Martha had already died, and he didn't believe on second Zings.