I think it's you that's watched too many movies--booze does not burn all that well. While splashing alcohol in 1 person's face and lighting it might, possibly, incapacitate that person, it is not any way to incapacitate the entire flight crew and all the other passengers. The end result would be an attacker struggling to not suffocate, because it is actually very hard to breathe when hog-tied, and especially with one or more knees in your back.
You can not "incapacitate the entire flight crew and all the other passengers" with knives either. But planes have been hijacked with knives before.