Continuity mistake: When Otho is calling the spirits of Barbara and Adam to return we see Barbara first, suspended above the table in her wedding gown. She "ages" so rapidly during Otho's chant that her skin shrivels and her feet curl up, causing one of her shoes to fall off onto the table. A few minutes later we see a long shot of both Barbara and Adam suspended above the table, but her shoes are both on and there is nothing on the table. (01:13:30)
Visible crew/equipment: When Otho is doing the Seance, Adam and Barbara appear in their wedding clothes and then float above the table. When Lydia releases Beetlejuice, everyone gets up and leaves the table, and in this wideshot the black wires that Adam and Barbara are suspended from are visible. (01:15:25)
Visible crew/equipment: When the small priest emerges from the fireplace and then when he goes on to do the wedding ceremony for Beetlejuice and Lydia, you can see a thick black tube running out of the priest's right leg, trailed behind him. (01:18:30)
Revealing mistake: When Maxie and Juno are jetted through the ceiling, check the stiffness of their bodies: they've been replaced by mannequins. (01:19:20)
Continuity mistake: As Adam speeds towards Beetlejuice's foot in the miniature red car, the amount and position of plaster and rubble around Beetlejuice's foot changes between shots. (01:20:40)
Continuity mistake: In the wedding scene at the end when Barbara comes crashing through the ceiling on the sandworm, Beetlejuice looks up at the ceiling, which is still intact, and screams - a split second later Barbara actually crashes through and the sandworm devours Beetlejuice. (01:20:45)
Revealing mistake: In the scene when Beetlejuice is getting married, you can see the priest in the fireplace after he supposedly burns up. (01:21:15)
Continuity mistake: When Lydia dances at the end, the two times we see the top of her head, her hair is parted differently. (01:23:20)
Continuity mistake: When Beetlejuice is in the waiting room at the end of the movie, he speaks to one man with a shrunken head, who does not reply. He then turns to the voodoo man sitting to his right, and he notices that this man has the a lower ticket number, so he steals this mans ticket and then throws his own ticket into the voodoo mans lap. But in the next shot the ticket is not in the voodoo mans lap, but it is on the seat beside his left leg. (01:24:15)
Continuity mistake: When the fly lands in the cemetery, the ground is some sort of spiked rubber. When the camera is flying in, we see the cemetery is actually dirt and sand glued to the board.
Other mistake: If the dead characters all are continuously displaying how they died, Adam and Barbara should constantly look wet, but they don't.
Revealing mistake: At the end when Lydia is being lifted into the air during the "Senora" song, if you look very carefully, you can see the wire lifting her up.
Continuity mistake: At the end when Beetlejuice is sitting next to the witch doctor he throws the number on his lap. When the doctor picks it up it's beside him on the chair.
Revealing mistake: At the end, as Beetlejuice's head shrinks, the collar has a line around it, showing where the two images were superimposed.
Continuity mistake: After Betelgeuse knocks down the model tree, Adam places it back into its hole. Later on, as the camera zooms in on the whole model, you see the tree is still on the ground.
Continuity mistake: The photos Charles is holding of the Maitlands in sheets are 35mm photos based on the shape of the photo. The pictures Lydia took of them were Polaroid which are square and not as detailed or sharp as the other pictures, much less the same shape even if they were blown up.
Other mistake: When Adam's headless body runs into the hallway to go shut the attic door, you can see a reflection of his body when he crashes into the banister. Ghosts don't have reflections, as seen in the beginning.
Other mistake: If the Maitlands cannot be seen in a reflection being ghosts, then Lydia would not have seen them in the attic window in her camera, as that uses a mirror to reflect the image through the viewfinder.
Audio problem: When Adam, Barbara and Juno walk into the attic, Juno says "You should have been studying those lessons since day one." However, her lips never move.
Continuity mistake: When the wedding clothes are laid out for the seance, there are no pants/trousers in place for Adam, but when he materialises he has them on.
Answer: Italy is the center of the Roman Catholic Church, which includes exorcisms as a real-life ritual. Presumably, ghosts in Italy are at greater risk of encountering trouble in Italy because of this reason.