Many changes after the pilot episode: The Walsh house changes to a different building (which explains the odd scenery behind James Eckhouse in the re-shot pilot scenes as it matches the Walsh house used in the remaining 10 years of the series, not the house used only in the pilot.) Also, Brandon's car changes from a Chevy Chevette in the pilot to a different model car in later episodes, referred to as "Mondale". Also, Luke Perry does not appear in the series pilot, he is first featured in the second episode. The building for "The Peach Pit" was also changed after a few episodes in season one.
In its early seasons, the show's episodes were issue-based until the producers decided it should become a teen soap opera.
The character of Dylan was only supposed to be on for one or two episodes.
Dylan's house exterior changed without him moving. The first outside shots showed a white house in a comfy neighborhood. Later it showed at dark wood house set back from the street and down a slight incline.
The name of the fictional series that Steve's mom was the star of was "Hartley House".
"West Beverly" does not exist. Beverly Hills High School would not allow the use of their name in the series.
Brandon's car nicknamed the 'Mondale' was named after Walter Mondale the United States Senator of Minnesota and the Democratic Party nominee for President in 1984. He lost against Republican Ronald Reagan who was re-elected.
In the first season, when Donna tries out for school DJ, she is referred to as Donna Morgan. Throughout the entire show, her name is Donna Martin.
In the first season Donna Martin's mother was named 'Nancy Martin' and played by actress Jordana Capra when she was reintroduced in season 2 she was named 'Felice Martin' and was now played by actress Katherine Cannon.
Potomac, Maryland, Darren Star's hometown, was the inspiration for the show, and was originally going to be named "Potomac, 20854". However, it was believed that more people could associate with and recognize Beverly Hills as opposed to Potomac.
"Mondale" is a 1978 Mercury Cougar.
The "gang" were juniors in season one, meaning they would graduate in season two. Instead they were juniors twice and graduated in 1993 in season three. However when they stayed juniors for seasons one and two, David Silver started as a freshman in season one and moved up to a sophomore in season two.