Indiana Jones 5: 7 Kingdom Of The Crystal Skull Mistakes It Must Avoid
4. Aliens

It goes without saying that the Indy franchise deals with the supernatural and the occult. From the Ark of the Covenant to the Holy Grail, a wide number of magical items have acted as MacGuffins at the centre of films one through three.
But then came Kingdom of the Crystal Skull, and the aliens it brought with it. It's not that this plot point was poorly executed - it was just fine - it's that it felt plain wrong, like it belonged in a completely different franchise. So what, there are aliens in this world now? How are we supposed to feel any sense of danger watching Indy square off against goons if we know that there are universe-crushing beings in space just waiting to go all Independence Day on us?!
The magic and the supernatural elements of the first three films weren't exactly grounded, granted - but they were exactly that. Magic. The aliens in Kingdom of the Crystal Skull were clearly a tangible, physical presence, and that made them stick out like a sore thumb.
On top of this, aliens are just plain boring. How many times have we watched a movie with an extraterrestrial villain? Indiana Jones is exciting because it introduces us to mythological artefacts and legends we've never heard of before, and Kingdom of the Crystal Skull completely abandoned that notion. Hopefully, the fifth movie dives deep into the well of historical intrigue and plucks out a suitable mystery rather than resorting to a cheap, easy galactic threat.