While at the prison, Castillo fires 7 rounds from a 6 shot revolver, and then holds an empty gun on the prisoners.
Notice that Tubbs is in a state lockup. All prisoners MUST hand-in all personal items when being processed. You can see that Tubbs, throughout the entire time he is in the lockup, you see him wearing his gold chain.
When Tubbs is at his desk, the typewriter is missing 3 keys, two letters and one symbol on the far left upper row.
In the scene, Castillo confronts Keller by the door as he is coming through it with a shotgun (44:09). Keller rapidly turns around, Tubbs isn't in the scene. All of the sudden, they cut the tape together, and Tubbs magically jumps on Keller. It looks like one of those reruns of "I Dream of Jeannie" as she blinks into a scene.