Word of God is the studio insisted Judge hire Aniston specifically so they'd have someone (anyone) famous for the ad campaign. He agreed because he thought she was right for the part and did a good job playing it but the studio wouldn't have cared either way.
The Danza: Jennifer Aniston's character is named Joanna. Joanna also happens to be Aniston's middle name in real life.
The printer that the main characters destroy, plus the computers they use in the office (and the OS).
Trope Namer: The Red Stapler — for the situation where a movie affects or creates a Real Life demand for an object, good or service. Swingline didn't make them when the movie was produced, but does now.
Truth in Television: That traffic jam in the opening credits? That's the Interstate 635 beltway in Dallas, notorious for traffic jams to this day.
Vindicated by Cable: One of the premier examples. The movie pulled in mediocre box office numbers, despite relatively good reviews from critics, but found a second life on premium cable and on home video. Comedy Central's frequent airings brought the movie to an even wider audience, quickly granting it Cult Classic status.
What Could Have Been: After the first film's success on video and becoming a Cult Classic, Mike Judge was offered the opportunity to make a sequel to the film. But making the first film was such an unpleasant experience for him that he declined.
This early script contains a lots of differences, from Initech being named Nycor, Peter losing his temper a lot, Anne disliking Lawrence, and working at Unitrode (in the final film it's called Initrode and referred to a couple times), Joanna being named Jennifer (likely they had to change it to avoid a case of The Danza), and more.