Factual error: While hiding in the arctic cave, one of the minions eats a banana. However, the minions are supposed to have been trapped there for many years and edible bananas are restricted to tropical or near-tropical regions, roughly the area between latitudes 30°N and 30°S. It would not be possible for them to have bananas.
Factual error: When Kevin, Stuart and Bob are honored at the end of the movie in front of Buckingham Palace, the Union Jack can be seen flying on top of it. The only flag displayed on Buckingham Palace at that time was the Royal Standard, and only when the regent was in residence.