Chris Dunbar shaves a full beard with lather and a straight-edge. Men of that (or any other era) would know that the beard needed to be trimmed with a scissors first.
At 4 min 30 sec Marshall Earp enters the office and has trouble putting his hat on the wall rack by the door. Presumably, it should be an automatic action that he has repeated many times.
It's not explained why Shotgun Gibbs only turned the man on the buggy around, without bothering to look in the back.