Revealing mistake: When Allison is "seeing" the Massey house going up in flames, James flinches when the painting falls off the wall behind him, even though it is only supposed to be happening in Allison's vision.
Medium (2005)
1 revealing mistake in season 2 - chronological order
Starring: Patricia Arquette, Sofia Vassilieva, Miguel Sandoval, Maria Lark
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 to school with Joe, and Joe complimented her on her prowess.
Allison Dubois: It's 9:00. How am I supposed to know you're OK? How do I know you're not lying dead somewhere?
Joe Dubois: If something had happened, somebody would've called. If I were dead, who are we kidding, you'd be the first to know.
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.