The chair with Skip's coat on it changes position between shots. When Skip returns from speaking to the 2 fighting men, the chair has moved away from the table.
When Skip is thrown from the bronco the first time, he is wearing gloves. As he rolls over on the ground, he is not wearing gloves. When Grossberger picks him up, he is wearing gloves again.
When the new inmates are given a written diagnosis test and Skip is arguing with the guard, a pencil appears and disappears in his hand.
When Grossburger knocks out Jack Graham, as Skip is making his escape, his hat and sunglasses both come off, but in the next shot his sunglasses are back on, but his hat is nowhere to be seen.
When the guard is taking Harry to the infirmary, as they are exiting the screen to the left, you see an orderly sitting down at a desk or table. The very next shot, the same orderly is covering Harry in the bed sheets.
When Grossberger is singing, there are 5 men in a cell with only 4 bunks.
After Skip, Harry, Rory and Jesus escape from the prison rodeo, Meredith catches up to them and lets them know they're free because authorities have captured the real bank robbers before they all drive away. In reality, Skip and Harry could be charged with escape because they weren't officially released, and they could have been charged with aiding the escape of Rory and Jesus.
After Skip and Harry are arrested for bank robbery, they are sentenced to a state prison. Since bank robbery is a federal crime, they would have been sentenced to a federal prison instead of a state one.
While Skip is getting settled onto his bull at the rodeo, he is wearing a wristwatch on his left arm. Nobody riding in a rodeo would wear any kind of jewelry or unnecessary straps that could get caught and drag its owner around the ring, or possibly rip off a finger or hand. Even pant belts are disfavored by some riders.
Bank robbery is not automatically a federal crime. It depends on whether bank is federally insured or not. Also state and feds may agree to allow the state to prosecute depending on circumstances; as an example, state penalty may be more severe than federal. As a retired police detective I've personally investigated numerous bank robberies where the state has been the primary prosecutor.
One of the two robbers who impersonate Skip and Harry in the bird costumes is clearly played by a black actor, although the robbers are supposed to be two white guys. He's the one who punches a lady. Half of his face is visible under the mask, and his hand as well. (Possibly these two actors could be Richard Pryor and Gene Wilder themselves, since the bird costumes were custom-made for their size. Rather than pay for extras that are the right size to fit them, or pay for new costumes, the filmmakers could have used their two lead actors for the scene, which is very short anyway)
When Harry strikes the match on another inmate's chest, a small 'strike plate' can be seen on the center of the inmate's chest.
Caesar Geronimo uses alternating hands when riding the bull (Tornado). His right-hand is free while in the bucking chute, but his left-hand is free when leaving the chute (stunt rider).
When Deputy Wilson wakes Harry and Skip in their cell, he tells them the time is 4:30am. Daylight/Sunlight is shining through the cell window.
When the cowboy at the bar sends a punching bag flying across the bar and into some hanging lights, it is obvious that the punching bag is sent flying by the use of wires rather than the cowboys punch alone. Since it is suspended by wires the punching bag is seen bouncing unrealistically for several seconds after hitting the lights.
(In the scene where a trustee is giving water to the inmates, but gives water to Harry with a skimmer) It's clear that the working inmates are not doing any real work. There's a pile of dirt, and the inmates are just taking shovels of dirt and throwing them back at the same spot.
While Harry and Skip are discussing leaving for Hollywood at the bar, no one is playing either pinball machine, yet pinball sounds are heard throughout the scene.
It's never explained why the four escapees (Skip, Harry, Rory and Jesus) each go through different and complicated paths to get out, instead of going through the same way that Skip did. Also, it's never explained why Grossberger doesn't attempt to escape, and prefers to stay in prison (other than the possibility that the filmmakers didn't want the protagonists to help the escape of a mass murderer.)
How exactly would Meredith, or anyone outside of the prison for that matter, know that Skip's life was in danger at the rodeo? She is never seen interacting with anyone involved with the prison other than Skip, and he of course wouldn't have known that Graham and the guards were plotting against him.
A boom mic ducks into view in the long shot of the scene where Skip talks to the woman in the department store.
When Skip first finds Grossberger in his cell, Harry is stuck between him and the bunk bed, pleading with Skip. At the end of that scene, Erland van Lidth finally starts cracking up and smiles at Richard Pryor's antics.
Skip is shown with multiple changes of clothes in prison. None of the other prisoners has clothes other than a blue shirt, white t-shirt and jeans. Skip is shown wearing a gray sweater , a blue sweater , a yellow t-shirt , and a blue t-shirt (in different combinations) in multiple scenes.