Clearly PG-13! What happened?

How on earth did this movie get an 'R' rating in the US? There are no F-bombs, no nudity, no sex, little blood, and only a handful of deaths throughout the entire thing. When all of the dancers in a strip club are wearing 'pasties,' it's a good bet that someone was trying for a lower rating. Yes, two people got impaled (not very graphically), but there's far worse violence in every one of the Indiana Jones movies. So, I have to ask, why did it not get a potentially more profitable 'PG-13' rating? Anyone have any insight or details on that?