Factual error: When Robbie is shot at in the "Popemobile", the bullet comes through the glass. The whole reason for having it is because it's bulletproof. They started using it after John Paul II was shot in the early 80's.
Factual error: The real "Popemobile" is famously a Mercedes-Benz, the one in the film isn't. Whilst the film makes numerous factual errors for comedic purposes, it's very unlikely that this was intentional.
