Continuity mistake: When the Sheriff comes into Lili's dressing room, she has her left hand resting on the desk.When she takes the rose you can tell her left arm is down to her side now. When she tells the sheriff to have a seat, she only raises her right arm but in the next shot her left arm is raised with her hand in the desk again.
Audio problem: When Lili Von Shtupp is singing the "I'm Tired" song, an old, drunk cowboy stumbles onto the stage saying, "Oh my Miss Lili, oh my lovely angel, etc." but his lips are not moving at all. Right before she knees him in the groin, the overdubbed voice is still talking but the lips again aren't moving.
Continuity mistake: When the townspeople are saying their goodbyes to Sheriff Bart, Mongo clobbers a man wearing a derby next to him and the man falls to the ground. The next shot the crowd is still densely packed, but the man Mongo struck is not standing, on the ground, or anywhere to be seen - he has disappeared.
Continuity mistake: As the taxi Hedley is in approaches Grauman's Chinese Theater, watch the movie title "Blazing Saddles" on the marquees. It moves slightly as the camera pans to keep the taxi in frame. Also, Hedley's suit and face are spotless, despite entering the taxi covered in whipped cream. And, it was afternoon when Lamarr got the cab, but dark at the theater. The studio and theater are only four miles apart.
Continuity mistake: After Mongo punches the horse and it's down, the snout is pointed toward the chest. In the close up, the head is at a more natural angle.
Revealing mistake: As Bart grabs the black king, watch his hands. He claps his hands around the king, draws the toward his body, and they dip partially down below the level of the table. When he does that, he opens his hands just enough to allow the piece to fall out of the camera's range. Then Jim pulls out a duplicate piece he had in his holster.