When playing Blaine Fabin in "Red, White and Blaine," it becomes necessary for Dr. Pearl (Eugene Levy) to remove his glasses. Unfortunately, Dr. Pearl's glasses corrected his lazy eye problem. Actor Fred Willard was unaware of the gag during shooting, and after delivering the line "what did your keen and perceptive eyes behold?" to Fabin, stared at Levy's lazy eye, finally understood why his line was funny, and "was gone for about ten minutes" with laughter.
During the scene where Corky (Christopher Guest) is teaching the cast some dance moves, Eugene Levy can be seen in the back behind everyone, almost hidden from view. This is because whenever Guest would show off his moves, Levy would laugh so hard that they would have to cut and wait for him to stop laughing before doing another take. They figured it'd be best if Levy was in the back, where he would not be able to see Guest during this scene.
Don Lake was originally cast as the principal of the high school who had problems with the rehearsals taking up the basketball team's floor. When the character was ultimately cut from the story, Lake was re-cast as the town historian. However, all the footage of him during the performance of "Red, White and Blaine", including his intermission interview, is of him as the principal.