During the song "Shock Treatment" the number of used flashes on the instant camera increases and decreases between shots, rarely matching the number of pictures taken.
Farley's lazy right eye disappears intermittently throughout the movie.
During "Farley's Song," the "jazz hands" in front of the TV screen change position between shots. Most noticeably, Cosmo's hands move from top left to bottom left.
When Brad knocks over the pitcher of water on the "Marriage Maze" set, a glass is propped against one of the "M"s. The glass wasn't there in previous shots.
When Neely interviews Farley before the premiere of Faith Factory, Nation, Bert, Cosmo, and Ralph are in a corner, and Nation is pouring champagne. When the camera pans out, all four are drinking and the champagne bottle has disappeared.
During "Anyhow, Anyhow", when the gang are driving out of the studio, Frankie (Francine) is obviously running alongside the car instead of having gotten into it.
During "Denton, U.S.A." an extra in the second row doesn't lean to his right on cue, blocking half the row from leaning. A moment later, the extra on his right starts to lean left when she shouldn't, then stops herself.
The 2006 DVD release features a brief but noticeable audio dip right before the last chorus during "Denton U.S.A."
During the opening overture sequence, the shadow of the camera, camera operator, and jib operator are visible just after booming down from the spiral staircase.
During the finale, as the four singers rise from the bleachers, Ruby Wax trips and places her hands against Charles Gray's back to keep from falling over.