Plot hole: In this episode, the Duboises make such a big deal about Ariel being old enough to finally learn to drive. However, two episodes previously ("Things to Do in Phoenix When You're Dead") Ariel drove herself to school and Joe complimented her on her prowess.
Continuity mistake: At the beginning of the episode, Van Gogh starts painting blue circles "on" our TV screen (this is the 3D episode). The three circles are big and touch each other. Next shot, seen from a standard point of view, you see him getting back up and the canvas is still on the floor: the circles are smaller and quite far apart.
Factual error: 1-11: I Married a Mind Reader. A nitpicking mistake, but on the set of "I Married a Mind Reader", the front door is a modern steel design. Back in the 60's, front doors were almost always wood (steel doors weren't available until the 1970's or 80's), and the window design would have been larger on a 1960's fan-window wooden door.
Trivia: In "Four dreams" the alternative Allison who doesn't have children looks at some kids in a restaurant and gets a dreamy look on her face. The mother of the children she is admiring addresses her daughter as "Sofia". The "real" Allison's daughter Ariel is played by actress Sofia Vassilieva.
Trivia: In several scenes, for instance when Allison is talking to Teddy's ghost in the kitchen or when they're eating, you can see the names "Harlow" and "Enzo" spelled out in magnetic letters on the fridge. These are the names of Patricia Arquette's (Allison's) children. You can see the names separate and together in some other episodes too, but rarely as clearly as in this one.