Continuity mistake: When Adam and Barbara are sleeping, they awake to a sudden commence of the whole house shaking. There is one close shot of the items on the mantelpiece. Watch the items. There are reels of cotton on the centre of the mantel which vanish between shots, and in the wide shot a book has appeared in front of one of the photo frames, which wasn't there beforehand. (00:12:50)
Continuity mistake: During the scene where the new family eat dinner for the first time, there are candles in front of the dad (they are in metallic candle holders). They are in an order like large, small, medium. But in the close up shot of the dad they have changed places to medium, small large. The sizes may be different but the concept of the mysterious shape shifting candle holders is the same. (00:19:55)
Continuity mistake: When Charles and Delia are sitting out on the white terrace, Charles holds a glass with brown coloured drink in it which is three-quaters of the way full, and Delia's glass is half full. When Otho walks onto the terrace, Charles's drink is clear-coloured and the glass is filled right to the top, and Delia's glass is now three-quaters of the way full. (01:01:35)
Continuity mistake: During the scene where the Deitz family and their guests get possessed to sing and dance along to "Day-O," the positions of the black and white napkins, the wine glasses, the cutlery, the wine bottles in the ice-buckets, etc., change many times throughout this completely hilarious scene. (00:50:20)
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.
Continuity mistake: In the Day O scene. Lydia is sitting at the table next to her father. When the possession takes place, Lydia is not longer at the table and in a brief moment is seen in the corner hiding, laughing behind her chair. The camera closes in on the song and dance, and when pulls it back Lydia and her chair are gone and the corner is empty.
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.
Continuity mistake: When Charles is looking out of the window, he pushes one slat of the blinds upwards, and then bird watches with his binoculars. When Lydia comes in and makes him jumps, he turns around, and this particular slat falls back downwards, into place. But in the very next shot this same slat is pushed in an upwards position again. When he sits back down again as Lydia leaves, the slat is back down again. (00:27:35)