Deliberate mistake: The layout of the Walsh house, both interior and exterior, is different in the pilot than it is in the rest of the series.
Beverly Hills, 90210 (1990)
1 deliberate mistake in show generally - chronological order
Other mistake: When the show aired in 1990, in the pilot episode Brenda falls for Jason. She later on reveals herself to be a "16 year old junior" in high school. Season 2 opens up with the gang on summer break which technically would make them going into their senior year. It wasn't until Season 3 that they were going into their senior year. They graduated in 1993 from West Beverly but the show debuted in 1990 so technically they should have been sophomores.
Emily Valentine: This isn't Beverly Hills! It's Knot's Landing.
Trivia: When Brandon and Kelly leave the movie theater, they pass a billboard for The House of Yes, which co-starred Tori Spelling.
Question: Was Valerie Malone introduced this season to balance out Brenda's departure?
Chosen answer: Yes, she was.