In "The Day They Hanged Bret Maverick", Bret said his birthday was April 11. Here he says that it's May 11.
In the culminating scene, Bret enters the stables from the rear. As he crawls along on the floor, he carries a crescent wrench, which he plans to use to defend himself against the bad guys. But as he crawls along the floor, it wobbles, revealing that it is a rubber wrench.
Bret goes back to the bar to question the barkeep about his having identified him as THE BRET MAVERICK. Bret takes the barkeep into the backroom where they get into a fight. The barkeep throws a keg at Bret, who pulls a door toward himself in order to shield himself from the keg. The keg strikes the edge of the door, causing a piece of wood to splinter off. But it is obvious that this was NOT the first take for this scene. Before the keg strikes the door, there is already a chunk of wood missing from the very spot where the keg hits the edge of the door. So when the keg hits the edge of the door this time, it ends up not just taking out a chunk of wood, but at the very least a second chuck of wood from the door.