In the scene where the gang are at school and listening to the radio, the radio is a small purple model (shown in cap #1). Then after a scene with Lorena in the radio station, it comes back to the gang in the hall with more students, but this time the radio is bigger and black in color instead.
When it first came on and they were sitting down to eat, Dennis, put two things on his plate (a piece of bread and some kind of meat) His glass was empty. When their dad came downstairs, it flashed to his (Dennis) plate again and it was empty. Then Matt reached over and put a piece of bread on Dennis plate. This flips back and forth throughout this one scene! (Great catch DrkAngl778!)
In the last scene where Mark gets cake smashed in his face, Tony walks by wearing a pair of black shoes and then he's standing behind Mark and he has sneakers on. (Great catch Kim!)
In the episode " Love Letters" Tiffani tells the gang her regret about high school. She mentions that it happened Freshman year, October 1992. In the episode "Graduation" we see that the gang is PCH Class of 1997. High School is only 4 years not 5. Either Freshman year started Fall of 1993 (not 1992) or they graduated Class of 1996 (not 1997).
We'll Always Have Aspen
Near the end, Tony sees the lady he was chasing after and he goes up to her and says, "Hello, my name is ANTHONY..." And his real name is supposed to be Antoine. (Thanks to for sending this in!)
Shaken, Rattled and Rolled
In the first earthquake scene, Sam and Tiffani are looking to the side as the camera is to their left. In the next cut, however, the camera is right in front of them and they are facing forward, even though they never turned their heads. (From: TV.com)
E-mail me your mistakes and put "Bloopers" in the subject and I'll post them here. If you know which episode its from, let me know.