When Master refuses to fix the generator, Ironbar orders him lowered into the pigs. Master's overalls and arms are clean. A second later, before he reaches the pigs, his overalls and arms are suddenly muddy.
When Max "parks" his weapons, we hear the sound of 15 separate items (counting the shotgun shells as one item) hitting the counter, yet when he's finished, there are only about 7 items in the pile. Also, he puts his shotgun down second, on the right side of the counter. It immediately disappears for several shots and then reappears on the left side.
As Max is clearing the path for the plane, and just before he reaches Aunty's armada, he climbs out of his truck on the right side (where the steering wheel is). However, when he jumps off the truck, he jumps from the left side.
Ironbar fires an arrow through the train/truck's door and through Pig Killer's leg. The arrow has a huge four-bladed broadhead on it, yet the hole in the door and the hole in Pig Killer's leg are only the size of the arrow's shaft.
During Max and the children's attempt to rescue Master, they sneak into the underground in order to free him from the pigpen. At one point, as the escape is put into play, Ironbar arrives and hits Max in the face with a shovel. The problem is that in order to establish the shot and weapon used, the shovel stops abruptly in front of the camera as Max falls backwards, where, unfortunately, the rubber that forms the shovel's fake blade continues to jiggle from the motion.
The goof item below may give away important plot points.
During the runway discussion at the end of the film, Jedediah the pilot tells Max that Aunty's approaching motorized bandits are closing the space needed for them to take off. Max decides to drive a vehicle through the motorcade to clear space so they can take off. After this discussion, Max only collides with one vehicle and the aircraft is able to make it. This proves if they had taken off right away instead of having the discussion, there would have indeed been enough runway.