Continuity mistake: When Lydia first meets Delia, there's a man in the glass box behind her walking around. Between cuts, he suddenly moves back about five feet.
Continuity mistake: When Rory finds Lydia's pills and says "No," Lydia's mouth goes from closed to open between cuts.
Continuity mistake: When Rory is first seen at the studio, suddenly an extra production assistant appears behind him when it cuts from the medium shot to the extreme wide shot.
Continuity mistake: When Lydia introduces the guests on her show at the start of the movie, the way the woman is holding her dog "Taco" changes between cuts. (The dog goes from facing Lydia to facing away between cuts.) This sort of mistake happens several more times over the scene.
Visible crew/equipment: When Beetlejuice is first introduced, right before we see him, the camera rotates around the model and the sign above the grave lights up. Right before the sign lights up, you can ever-so-subtly see a part of the camera's shadow move over the model. It's subtle and easy to miss, but once you see it, it's pretty obvious.
Answer: I thought the same thing on this and also why Lydia's husband was a civil worker, but there's a blink-and-you'll-miss-it part where Beetlejuice is reading a newspaper and there is a small story with a headline titled: 'Workers Wrongly Assigned Suicide at Death', which would explain it.
ctown28 ★