Continuity mistake: In this episode, Steve Urkel appears, depicted as a real person. But Urkel also appeared in a few episodes of Full House, which, within the universe of Step by Step, is a fictional television series.
Visible crew/equipment: When they are taping the family, Carol gets mad and goes upstairs and the camera guy taping her tapes her going up the stairs and when he does, for a second, you can see where the set ends and all the lights.
Revealing mistake: When the band is playing the show at the end, JT is supposed to be playing the bass, but anyone can tell he is not, even when the bass sound is used.
Answer: From what I've read, the kid in question was the original actor cast to play Mark and was intended be closer in age to Brendan. For whatever reason, they recast the role with Christopher Castile and didn't bother removing the original actor from the beginning of the opening credits. I guess they figured people would just assume the kid was one of Brendan's friends.
Phaneron ★