Other mistake: During the closing theme (early seasons), when Fred walks by to close the birdcage, Wilma is shown in the background sleeping and her entire mouth is missing.
Other mistake: When Ralph Mason walks into Walker's Drugstore and asks to purchase a tin of pipe tobacco, the tobacco tin that Ellie puts on the counter has black tape across the top covering its brand name, which is "Tuxedo."
Other mistake: In "Violent Is The Word For Curly" (1938), the Stooges are mistaken for college professors. They are teaching a group of students at the all-girls school Mildew College to sing "Swingin' The Alphabet." During the song, the girls sing "Curly's a dope." The dean had introduced the three men as Professors Feinstein, Frankfurter and VonStupor - so how did the girls know Curly's name?