When Barney backs out of the cave, the gold pieces that were lying on the ground are gone.
After the pickaxe falls out of the rock, it is lying in front of the cave. Barney goes to get the dynamite, and, when he looks back at the cave, the pickaxe has moved to the right of the mouth of the cave. When he lights the stick of dynamite in the mouth of the cave, the pickaxe has disappeared.
After Barney Bear lights the keg of gun powder the mule runs and hides next to an open crate of dynamite that was not there previously, it had been blown up earlier by Barney Bear.