Minor Plot hole: Nuke the Fridge. (That should explain it all)
Minor Plot hole: The Soviet agents are using an enormous heavy machine to cut trees in the Amazon in order to create a route for their vehicles to travel on. After Indiana Jones blow it up with a bazooka, the Soviets and the good guys get into an impressive car chase deeper into the Amazon. What created the roads they were traveling on ?
Minor Plot hole: The crystal skull power of magnetism changes depending on what the script needs. At first, it is strong enough to attract gun powder from hundreds of meters away, then it seems to have no effects on guns in certain scenes and no effects on cars in every scene. Plus, it can also magnetically attract gold....that's interesting.
Minor Plot hole: During the car chase in the Amazon, Mutt falls off a car and is left alone in the jungle. He however finds monkeys with whom he can swing around on vines to reach the other main characters who were still transported in cars that never stopped rolling. Mutt sure was fast. How could he be faster than everyone else ?
Plot contrivance: Poison-tipped blow darts are poisonous both ways.
Plot contrivance: When Ox appears in the quicksand scene, Indy gets the brilliant idea to tell this crazy old man to "GET HELP!" before he gets to drown in the mud. Was he surprised at all that the help that arrived were the same Russians they had just escaped from? Who else did he think was within 100 miles of them deep in the jungle? Either you accept their help like a respectful dying adventurer or you don't ask for help at all.