Continuity mistake: Taz (lead singer of group Donna and David are producing a music video for) recognizes Kelly from her 'Seventeen' magazine cover and mentions it was in spring (May) 1994; however that was still the gang's freshman year in college (Season 4) and Kelly did not do the Seventeen shoot until season 5, and the magazine cover was out in the spring of 1995.
Continuity mistake: When Steve is talking to Valerie, after getting out of the shower, about Coming Home early to surprise Claire, you can see shaving cream on his ears. When the shot changes to a side view of him sitting on the bed, he no longer has the shaving cream on his ears. When the shot changes back to looking at him head on, the shaving cream is back on his ears. This goes on for the entire scene.
Answer: There was no explanation. Usually, when a show doesn't know if it's going to be picked up or not, they will use stock footage until they can spend the money on a real location.
bucade