Goof: After the concert, Stan is telling stories while Dude looks out the window for his dad. When Stan notices, Dude turns to talk to him, and lets go of the window curtain. A split second later when it changes to the next shot, he's seen letting go of the curtain again.
Goof: When McRitchie tells Jason to have his ex-girlfriends call him, he puts his hand on Jason's shoulder. In the next shot his hand is by his side.
Jason: So you wanna go out sometime?
Amy: You mean, go out go out?
Jason: That's exactly what I mean. (Looks at a surprised Amy as the series ends)