Revealing mistake: At the beginning of the episode, as Jim West walks away from the newsstand vendor and closes the magazine, a 1967 ad for DieHard batteries ("The DieHard Fights the Common Cold") can be seen on the right-hand page of the prop magazine, in a modern sans serif font.
Continuity mistake: In the scene before the third freeze frame, a large coffin-like rectangular object slides into the water. West is inside this structure. All sides are completely flat. We see the object under water sinking. This one is much shorter, has an oval window, and the side is not completely flat when compared to the one that enters the water. After the freeze frame, West is sitting up with his legs completely extended. The dimensions of this under water container would have to have height and width much longer than the other two containers that have been shown.