Revealing mistake: When Barbara and Adam are digging up Beetlejuice's grave, you can see that a piece of cardboard states "FRAGILE" or something in small print which is proportional to Barbara and Adam at that time. However, the lettering should be ten times larger if the cardboard was proportional to the actual model.
Revealing mistake: When Barbara is moving the little plastic horse in front of the mirror to prove that she's invisible, the "reflection" of the horse is not synchronised with the actual horse.
Continuity mistake: When the Deitz family first check out the house, Otho shakes up a can of spray paint, takes off the cap, and hands it to Delia. When it cuts to the next scene, you can see Delia take off the can's cap again.
Continuity mistake: When Otho is going through the house suggesting changes he is wearing white sneakers in one room and red ones in the next.
Continuity mistake: When Barbara tears the top of the wrapping paper off of the present (tube of wallpaper) Adam bought her, in following shots the way the paper is torn and the way it hangs, changes. In the very next wide shot the whole of the wrapping paper is suddenly off of the tube of wallpaper, without enough time given for Barbara to have pulled it off. In following shots Adam and Barbara kiss and cuddle on the couch, and in one shot you can see that the wrapping paper had reappeared, and is still wrapped around the tube.
Continuity mistake: In the part where Barbara and Adam are asked to draw a door on a wall in case of an emergency, there is already a chalk outline of where a door would be.
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.
Revealing mistake: In the scene where Barbara is showing Adam that they have no reflections by moving the horse in front of the mirror, Adam's reflection can be seen in the windows in the background.
Continuity mistake: After drawing the chalk door, Adam knocks on it three times, and then it opens. Adam then sets down the "Handbook for the Recently Deceased" and puts the piece of chalk down next to it. But later, when Lydia sneaks up into the attic, she finds the handbook, now with the piece of chalk sitting on top of the book.
Continuity mistake: The distance between the picture hanging on the wall and the light switch wire often changes through the movie. Look at the distance between the two when Adam walks past to throw the spider out of the window. When Barbara pokes her head into the room in the following shot to give Adam his present, the picture now hangs right beside the light switch wire
Revealing mistake: When Beetlejuice rises from the grave, and then flies after Adam and Barbra, for a split second, you can see a wire over one of his shoulders, but it is pretty hard to spot.
Revealing mistake: When Adam, who should have no reflection, walks out of the door to go retrace his steps, he is really clearly reflected in the big glass panel in the door. Then after Barbara pulls Adam from the SandWorm land, they walk back into the house through the same doors, and are both reflected in the glass panels of the door. So much for ghosts...
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.
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.
Revealing mistake: When Lydia is writing her "suicide note" she crumples up the first one, the papers stick together and the paragraph for the second is visibly already written.
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.