About 40 minutes into the film, when Slip enters the saloon firing his pistols into the air, a cut to the cover shot shows a saloon gal and cowboy with black hat, oblivious to the gunfire, moving around a table and to our left. Cut back to Slip firing a few more rounds and then back to the cover shot which shows the same sequence of the cowboy and the gal walking around the table.
When the gang meets the group of Indians on the way to Hangman's Hollow, Sach shows the map on his back to one of the braves, but when they return to the group (at 18:37), Sach's back is clean.
The Indians shoot two arrows into the cover on the gang's car, but in the next wide shot, only one is seen; and, at 15:27, up to seven arrows can be seen sticking out of the cover.
When Slip gets an arrow through his hat, multiple holes are visible; clearly this was not the first take and they had no back-up hats.
When the boys raise and lower Blackjack from the barn, the rope is slack when it should be taut from supporting his weight. The wire that is actually part of the rig raising and lowering Blackjack is plainly visible.
When Slip gets an arrow through his hat, a small portion of the guide-wire used for the effect is visible to the right of his hat.
When the sheriff arrives in front of the sweet shop, he casts two shadows on the painted backdrop of the street, proving that it's a poorly lit interior shot.
Though the timing of the strumming hand is very good, one can tell by the fingering that Louie (Bernard Gorsey) isn't playing his banjo.
When Catherine starts singing "Two Gun Tilly" at the saloon, the audience applauds but makes no sound.
It's rare to see Leo Gorcey break character. At 8:15 while in a heated conversation, Slip slaps Louie and Louie slaps him back. As Slip turns his head to watch Louie go, he smiles, showing amusement and making it seem as if the slaps were both improvised. (Louie smiles briefly right after the slap, amused as well.)