In the medium shot of the Stone Age soothsayer scene, Buster's hands are resting together near the side of the turtle. But in the cut to a close-up, we see only a hand double's right hand, and it's directly in front of the turtle's mouth. (It's clearly a hand double, since Keaton was missing his right index finger tip.)
As Buster is driving to Margaret's house, his porkpie hat is battered. But when he arrives, it's fresh and undamaged, and looks brand-new.
The water level in Buster's carafe fluctuates. He nearly drains it, then in the next shot, it's half full.
In the modern section, the newspaper announcement of the wedding varies. The first time it is seen it has five lines of text, but the next time it only has four.
At almost exactly halfway through, there is a scene of a scientist/ weatherman writing down the weather report. Hanging behind him is a clock. The time period is supposed to be that of ancient Rome, but the modern clock wouldn't be invented for well over 1,000 years. They would still be using sundials.