In the whore house scene where the towns people mistakenly shoot the sheriff, Billy explains in voice-over that he was blamed for that killing though he never even fired a shot. This is an error as Billy clearly fires the first shot as he pushes the sheriff out of the front door inciting the towns people to open fire on who they think is Chavez the Indian.
After his capture, when Billy is in the room with Deputy Bell, there is a knock on the door, Deputy Bell cocks his Winchester, putting the hammer back in the firing position. When the door opens, the Madam, Jane Greathouse, is standing there, Bell has the Winchester at his shoulder and the hammer is in the down, or fired position.
In the scene where the gang is surround by Garrett's men and Doc is shot, Arkansas Dave Rudabaugh is seen standing straight against the wall holding both guns up, after Billy hands Doc a second gun, Arkansas Dave Rudabaugh can be seen crouched with the right hand gun parallel to his side. In the next shot he is standing against the wall again with the guns held up.
In the White Oaks whorehouse, just as Billy agrees to send an Indian out to satisfy the crowd, we see Dave getting up from the table. In the very next shot Dave is stood next to the Sheriff, tapping him on the shoulder.