Well, according to my DVD of Airplane!, where I sat there and watched every credit roll by, there’s not one mention of anything weather or safety related.
IMDb pretty much accepts what its users submit to it at face value, and is not above having errors.
… nor, for that matter, does the second Naked Gun movie have any tornado-related advice in its credits. (I just checked.)
This is true. I suggest you tell them to fix the credits (assuming you haven’t done so already).
OK, so I was wrong. The “In case of tornado…southwest corner of basement” credit was at the end “Police Squad: The Naked Gun” and not “Airplane!”. It’s still pretty good advice.
I just want to say good luck. We’re all counting on you.
If they find out you’ve seen this, your life will be worth less than a truckload of dead rats in a tampon factory.
Oh! You have a guitar! 
The fake-out in NAKED GUN did it for me.
Over and over, a gag pops in and then leaves. Frank shot some toga-clad weirdos? That only exists to set up a response; it then never needs to get referenced again. Jane just had a beaver stuffed? Funny; now drop it, and move on to the next bit. Sleuth looking for a clue says “bingo,” and then we see why? One and done.
And so you write stuff off. And then a guy shouts, “Hey, it’s Enrico Pallazzo!”