In the counting wagon there is a small American flag with 50 stars. In 1908 (the year of the film) there would have been 45 stars, or if the flag was brand new it would have had 46 stars on account of Oklahoma joining the Union the year before.
The seven-shot six-shooter: Joe Knox and Billy (Oliver Reed and Strother Martin) are cavorting on a large log that has fallen across a creek. Sam Longwood (Lee Marvin) pulls out his revolver and shoots at them, clearly firing off seven shots from a six-shooter revolver.
When Sam was chasing the wagon driven by Thursday, he falls down and his hat is missing. In the next scene, showing Thursday driving and Sam getting up in the background, his hat is on his head as he gets up.