The Boston Globe ran a piece about a podcast about a real snake on a plane (I guess they were starved for news):

So forget the movie, and head over to pilot Joe d’Eon ’s website, Fly With Me. (Use a search engine and find the podcast Fly With Me Episode 12.) What you’ll hear is a flight attendant telling the story of what looked like a non poisonous snake that showed up between the windowpane and fuselage of a L-1011. The flight was full, so the captain asked the passengers if they wanted to be delayed forever while the plane was taken apart, or whether they wanted to fly. They opted to fly, and when the plane landed . . . the snake was gone.

I won’t spoil the story, but let’s just say when the plane took off the next time, the passengers weren’t told about the snake, which had disappeared. Or had it? So yes, there can be snakes on a plane, and they can be scary.

Without Monty Coles, this just isn’t a real story.