Wyatt asks Doc Holliday to stay awake because Johnny Ringo might try to break Charlie Parks out of jail. Yet Wyatt, Doc and Gibbs all leave the jail and Parks unattended while they go follow Judge Spicer in case he gets in trouble with Ringo.
Wyatt, Gibbs and Doc break into Alma's hotel room and search it for evidence that she's involved with the robbery. There is no scene before this that tells the audience what led them to suspect her.
In this episode, and just about any others that have Judge Spicer trying a case, he uses a loaded pistol as a gavel. Something could happen that makes the gun fire when he bangs it on the desk.