Other mistake: When Mutt is riding his motorcycle the first time he meets Indy at the train station, his hand is pulling in the clutch as he rides. But with the sound and speed of the bike, the clutch would have to be out.
Other mistake: In the warehouse scene when they're standing around the crate containing the heavily magnetized alien, all metal objects like guns and other items are pulled towards the magnetic force field. But Indy, who is standing next to the crate, has a bag with a metal strap that stays still when it also should've been pulled towards the alien.
Other mistake: When Indy escapes on the rocket powered train, it is slowed down by a pool of water on the tracks. The only problem is that when this happens in real life, it's almost the same as slamming into a wall, and therefore Indy should have been flying several feet away from the rocket powered train. You can actually see the chair that the test persons before him used, and it has double seat belts on it.
Other mistake: In the scene when they are all inside the temple with the skeletons, the Russian woman takes the skull and walks up the stairs directly in front of the creature. Yet there are no direct steps. All steps leading up to the skeletons are a little off to the left and right, and there are two sets of them.
Other mistake: Spalko is hanging from a tree to avoid the sting of the ants. When a CGI ant is on her knee she closes both legs and smashes it. If you watch closely you'll notice that when she closed her legs the ant was already over her thigh, so if it had been a real ant it would have been impossible to kill that way.
Answer: People felt it was ridiculous and cartoonish, even by Indiana Jones standards. Even if it was possible to survive a nuclear blast via the lead lining of a fridge (it's not), or that the fridge would simply be thrown away rather than be melted/torn apart like everything else in the vicinity (it wouldn't), the impact of being flung what appears to be a mile or so through the air, then violently crashing into and rolling over the ground, would certainly kill anything inside. The controversy arose because usually, in "classic" Indy films, the fantastical elements were exactly that: fantastic, magical, and/or supernatural. This was presented as taking place in our reality, with no "power of God" or magic spells, and for many, that was just too much disbelief to suspend.