Continuity mistake: In the scene with the crucifix, Chris falls to the floor after Regan bashes her in the face. Look closely at the dresser that eventually comes sliding across the room at her. When we first see it, it's about half a foot to the right of the closet door on the left of the room, and is never touched or moved. When we see it again as it comes sliding across the room at Chris it's been moved to the left right up against the closet door. (01:19:10)????
Continuity mistake: After she gets up from the table, Chris walks into the kitchen and we see an oil and vinegar tray on the lower level of the shelf above the cutting board. We see this spot before behind Det. Kinderman as he looks at his coffee, and the oil and vinegar tray are not there. (01:16:00)????
Deliberate mistake: Det. Kinderman walks up the stairs where Burke Dennings fell to his death and looks up at Regan's window. This could not possibly be the outside of her window because when we see the room from the inside as Chris closes the window near the beginning of the movie, there's at least 6 to 8 feet between the window and corner of the house. Now when we see it as he looks up, the window is right at the corner of the house. (01:12:35)????
Continuity mistake: As they talk, Det. Kinderman describes how Burke Dennings was found, "with his head turned completely around, facing backwards". In the next shot they're standing in a different place. At first Father Karras has a shiny fence clamp on the right of his head than in the next shot it disappears. (01:05:20)????