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.
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.
Class of Beverly Hills - S1-E1
Factual error: In this debut episode of the show, Andrea takes a bus home to "Van Nuys." After showing the bus heading to the valley on the 405 freeway, as she exits the bus, the street sign states "Gramercy Pl" which is in L.A. (not Van Nuys or the San Fernando Valley where she is supposed to be in). In addition, her house shows 548 to be the address. All addresses in Van Nuys are either four or five digits.
One on One - S1-E5
Continuity mistake: They say it's October, but it was November in the previous episode.
Perfect Mom - S1-E7
Continuity mistake: When Jackie walks out and Cindy walks in, she closes the door behind her. However, despite the door being closed, Brenda walks in. (00:36:05)
Perfect Mom - S1-E7
Continuity mistake: In this episode we are (at the fashion show) introduced to Donna's mother for The First Time. She is called on stage as Nancy Martin. In all further episodes she is known as Felice Martin.
Visible crew/equipment: When the scene changes to Brandon, Brenda and Dylan going to the movies, look closely. You will notice Brenda waiting for Dylan in front of the movie theater. Then later, they show the exact same scene when she is waiting for Dylan to show up on their movie date. It's very quick, but the editors apparently didn't catch it.
Stand (Up) and Deliver - S1-E17
Visible crew/equipment: When Brenda is talking with Michael Miller, you can see a microphone come into the top of the frame.
Stand (Up) and Deliver - S1-E17
Character mistake: In one scene Brenda refers to Brandon's political opponent as "Michael Miller" but a few scenes later David refers to the same guy as "Robert." He's referred to as Robert for the remainder of the episode.
Continuity mistake: In season 1 episode 12 while playing ouija board Brenda says she "doesn't know any dead people", but in this episode it's revealed that her aunt died 2 years ago from cancer.
Visible crew/equipment: In the hotel room with Brenda and Dylan, right before he picks her up and puts her over his shoulder there's a mic drop in the top right corner.
Continuity mistake: In the beginning of the episode Brenda takes her mom's coat to drama class and is wearing a blue shirt and white biker shorts. That night the parents go to the beach club. The next morning before school they show Brenda holding the coat and again in the blue shirt and white shorts she wore the "day before."
Summer Storm - S2-E3
Visible crew/equipment: A mic drops into view when Brandon asks Kelly who she is looking at while she is staring at Kyle.
Camping Trip - S2-E7
Visible crew/equipment: Dylan goes to the newlywed cabin and Brenda follows him. When she opens the door and says "can I join you" there a mic drop in the center of the top of the screen.
Visible crew/equipment: During the opening scene when the man is counting to 90 seconds there is a mic hanging in the top center the entire time.
Necessity Is a Mother - S2-E10
Visible crew/equipment: Near the beginning of the episode, Brenda is sitting next to a tree talking to the group after Dylan gets up to leave, and a visible mic comes into view hanging center top of the screen.
Leading From the Heart - S2-E11
Visible crew/equipment: When Kelly goes to the Walsh's house to speak with Bobby in the morning, a microphone becomes visible at the top of the screen while the two are sitting at the kitchen table. (00:42:00)
Leading From the Heart - S2-E11
Visible crew/equipment: At the end of the episode when Brenda is backing out of the driveway, Jim and Cindy are watching her but you can also see someone standing on the porch in the background.
Down and Out of District in Beverly Hills - S2-E12
Visible crew/equipment: Kelly, Steve, Andrea, Brandon, and Dylan are all gathered near the lockers when Kelly begins to discuss her opinion of Steve's new girlfriend Christine. Just after Steve says "Tell me everything that's wrong with Christine", the camera pans to Kelly where a microphone becomes visible at the top of the screen. (00:15:15)
Character mistake: When David encourages the gang to dance at Scott's birthday party, David mistakenly calls Kelly by her actress' name, Jennie Garth. He says, "Scott, you're off, Buddy. Jen, kind of getting into it."
