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.
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)Bk04
Continuity mistake: Brenda goes to see a counselor about the robbery. She asks what to do about the nightmares. The counselor asks about her happiest moment. Brenda starts talking about her horse she had as a child. She starts out saying his name was Sebastian but by the end of her story she says his name is Sylvester.
Continuity mistake: This is the first episode in which Kelly celebrates a birthday, and it is in March. A few seasons later, Kelly has another birthday, but this celebrated in one of the first episodes of the season and takes place when everyone has just returned from their summer excursions. This would put her birthday in September.
Other mistake: Throughout the entire 4th series and even various times into the 5th series, pay attention to the shots that show the outside of Steve's Kappa Epsilon Gamma frat house. Every single time, you will notice the same exact two people outside of the frat house - one is a guy wearing a green and white striped shirt sitting in the lawn reading a book, and the other guy is wearing a brown or orange shirt lying on the couch outside. While not impossible, these same exact two characters wearing the same exact clothes doing the same exact things outside of the frat house every single time for upwards of a year or more in 'show time' is unlikely.