If you were expecting hugs and cupcakes in The Temple of Doom, we're a little worried about your understanding of the word "doom." This flick is dark.
But if you've never seen this movie before, especially if you're a young'n, it can be super-shocking and very violent. Hearts are ripped out, people are burned alive, children are whipped, and many, many bugs are crushed and eaten.
Because the PG-13 rating didn't exist at the time, Temple of Doom was almost rated R because of the gore. The PG-13 rating was created after Temple of Doom, which is PG, allowing for large quantities of (mostly) bloodless violence to fall into a less-than-R category. (Source)
The American movie industry wouldn't be the same without that rating. Iron Man. Captain America. The dinos in Jurassic Park. They all have Indy to thank.