Thanks for joining us on Apple Support Communities!
I understand that it can be disappointing to not get to watch a movie you were planning to watch. I'm happy to help point you in the right direction from here.
For help with iTunes Store purchases, take a look at this article:
Get help with an item purchased from the App Store, iTunes Store, or iBooks Store - Apple Support
For future flights, here's an article with some steps to help make sure the movie you purchased is downloaded to your device:
Redownload apps, music, movies, TV shows, and books from the iTunes Store, iBooks Store, and App Store - Apple Support