After Zeno changes clothes with Dr Smith, Zeno goes to hand him his gun, with the handle and trigger parallel to the ground. After Dr Smith refuses to take it, he pushes it back. When the camera angle changes back to Zeno, the orientation of the handle & trigger change to pointing downwards.
While Zeno (posing as Dr Smith) is talking to the robot after the robot finds him, Zeno tells the robot he is still a little fuzzy-minded after being hit over the head with a pistol. The length of the robot's "neck" changes between camera shots.
After changing clothes with Dr Smith and giving him his gun & hat, Zeno pushes Dr Smith towards where he believes Will Robinson to be. Immediately after pushing Dr Smith, the side of Zeno's face can be seen, and it is a stand-in actor.
When the enforcer is locking the jail cell you can clearly see that there is no bolt in the lock.