1x22 - The Time Tunnel

Doug and Tony arrive in Lincoln in late April in the 1860s, and run afoul of Billy the Kid. Doug shoots Billy and apparently kills him, then he and Tony escapes. It turns out Billy took the bullet in the belt buckle, and he goes after the two. They manage to capture him thanks to a voice-transmitted distraction provided by Kirk, but Tony goes back into town and is mistaken for Billy. Pat Garrett arrives and eventually convinces the sheriff that Tony isn't Billy, but the mob isn't hearing it. Billy catches up to Doug and challenges him to a gunfight. Pat and Tony get involved, with Tony knocking out one of Billy's men planning to backshoot Doug and Pat intervening when Doug blows it. The two men are whisked off again.