Revealing mistake: When the plane crashes in the tree the wires holding it are visible. (00:17:55)
Revealing mistake: When the rhino is pursuing Ann, it's obviously a fake rhino with several wires attached to it making it move. (00:24:40)
The Gods Must Be Crazy II (1989)
2 revealing mistakes - chronological order
Visible crew/equipment: When the cheetah (an obvious fake dummy) pops its head inside the plane, you can see the crew member's hand and glove holding the dummy. (00:38:50)