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.
Other mistake: The tenant board member tells George that Mr. Eldrige in apartment 8C has decided he wants the new apartment. However, the new apartment in question has a 3-digit number - 808 I believe. This indicates that the building would not have single digit numbers and letters (Such as 5E, 8C, etc.) as part of its numbering system.
Other mistake: When they are showing the rap sheets for the Cambodian man, the race on the sheet says Caucasian when he is Asian, and for the African American man, the sex says "F" when he is male.
Other mistake: When Cooper is on the floor after being shot, as he's signing the check, he is doing so with the pen closed, and proceeds to click it open as he hands it back to the room service.
The Man in the Long Black Coat - S2-E8
Other mistake: Eric Idle is called Dr Melvin Whale, but according to the subtitles he is called Dr Melvin Mile.
Did the Earth Move For You? - S2-E1
Other mistake: Viv and Phil are waiting in his office for the power to come back on after the earthquake, but you can see lights on in the building across the street. (00:16:30)
Claudia and the Secret Passage - S1-E8
Other mistake: Claudia blows the dust off the paper she found after she opens it, despite the fact that it was folded up and taped closed.
Other mistake: When Mario is breaking some Blocks to find some Super Leaves, some of them remain intact. (00:03:42)
Safety in New York (or, Bertie Sets Sail) - S3-E1
Other mistake: When Tuppy goes to turn off the burglar alarm for Wooster, it's behind a hidden panel with a sign saying "Alarm Switch" above the panel. Why bother putting the switch behind a concealed panel if you're then going to label it? (Unless you're doing it for a viewing audience). (00:35:00)
Other mistake: When Fay is talking to Lowell over the walkie talkie, when she is giving him the recipe she is not pressing the button to talk, but Lowell still responds.