Looks like we picked the wrong week to quit celebrating milestones.

Hard to believe it's been 35 years since "Airplane!" took flight (on July 2, 1980) and taught us all to speak jive, order the chicken instead of the fish, and avoid calling each other "Shirley." Three and a half decades later, the airline disaster parody remains one of the funniest films ever made, one that generations of viewers have watched over and over -- though probably never as an in-flight movie.

Still, as many times as you've seen it, there's much you may not know about how it was made. In honor of "Airplane!" turning 35, here are a few facts every fan must know about the comedy classic.

1. Strip away all the jokes, and "Airplane!" is essentially a remake of a little-known 1957 air disaster movie called "Zero Hour!" The writing/directing team of Jim Abrahams, David Zucker, and Jerry Zucker lifted the plot, some of the character names, much of the dialogue, and the exclamation point in the title from the film. "Zero" was written by Arthur Hailey, later famous as the writer of the original "Airport."

2. The ZAZ team discovered the old film during their practice of taping late-night TV in order to find commercials worth spoofing in their sketch comedy troupe, Kentucky Fried Theater. They copied the script as an exercise in learning how to write a screenplay. But their original screenplay for "Airplane!" also incorporated parodies of late-night TV ads.

3. The "Airplane!" script borrowed so much from "Zero Hour!" that ZAZ took the precaution of avoiding a copyright infringement suit by buying the remake rights, for a grand total of $2,500.

4. ZAZ wanted to direct their film as well as write it, but they didn't have the clout to do so until the success of "The Kentucky Fried Movie," the 1977 sketch anthology that included ad spoofs of the sort that were trimmed out of the "Airplane!" script.
5. To play the hero, Ted Striker, Paramount wanted ZAZ to cast a conventional comic lead, like Chevy Chase or Bill Murray. But the filmmakers wanted someone who could work on their deadpan comic wavelength. Among those who auditioned for the role were Bruce Jenner and a then-unknown comic named David Letterman. (Yep, that happened.)

6. Ultimately, the part went to Robert Hays, who had to shoot much of the picture rushing back and forth on the Paramount lot between the sets of "Airplane!" and "Angie," the sitcom in which he co-starred. One plus: Hays was actually a licensed pilot.

7. A pre-fame Sigourney Weaver auditioned to play the heroine, Elaine, but the filmmakers have said she balked at the line "... sit on your face and wriggle." The role ultimately went to Julie Hagerty, who made her film debut in "Airplane!"

8. The co-pilot role played by basketball titan Kareem Abdul-Jabbar was a nod to a similar role played by football star Elroy "Crazylegs" Hirsch in "Zero Hour!" Originally, ZAZ sought Pete Rose, but the diamond legend was too busy playing baseball to be available for the August shoot. The studio offered Abdul-Jabbar $30,000 for the part, but his agent talked his fee up to $35,000, the price of an Oriental rug the Lakers star wanted to buy.

9. The supporting cast consisted largely of stone-faced actors known for playing serious roles in similar films. Robert Stack, who played Rex Kramer, had starred in 1954's "The High and the Mighty," one of the first air disaster films.
10. Lloyd Bridges, who played air traffic controller McCroskey, had starred on TV in the drama "San Francisco International Airport." ZAZ had sought "Airport" franchise mainstay George Kennedy for the role, but he and Universal felt that appearing in the spoof would damage the franchise.

11. Similarly, the filmmakers sought Helen Reddy to portray the singing nun as a spoof on her role in "Airport 1975," but Universal wouldn't let her. Instead, the filmmakers cast Maureen McGovern, known for singing the themes to disaster movies "The Poseidon Adventure" and "The Towering Inferno."

12. Peter Graves, best known for starring on TV's "Mission: Impossible," got the role as Capt. Oveur in part as a nod to his role in the TV air disaster movie, "SST Death Flight."
13. Leslie Nielsen, who had played the doomed ship captain in "The Poseidon Adventure," rounded out the cast as Dr. Rumack. Of course, "Airplane!" launched a second career for him as a deadpan comic leading man in movies from the "Naked Gun" movies to the "Scary Movie" horror spoofs.

14. While Nielsen is better known these days for his three decades of comedy (he died in 2010), he was still known at the time of the film's release as a stoic dramatic actor like Stack and Graves. But he insisted that he had always wanted to be a comedian, only no one had ever cast him in a funny role.

15. To prove his comic bona fides, and to break up the cast and crew, Nielsen traveled everywhere with a handheld whoopee cushion. He sold the devices to others on the set, until the shoot was so preoccupied with fart noises that the filmmakers had to confiscate them all.

16. The military pilot with post-traumatic stress disorder (watch below) who thinks he's Ethel Merman was played, of course, by Ethel Merman. It was the last movie for the 72-year-old musical theater legend.
17. To play the grandmotherly white lady who speaks jive, the filmmakers wanted Harriet Nelson, but she felt insecure about the language. Instead, they got another 1950s sitcom mom, Barbara Billingsley. Her "Leave It to Beaver" had been one of the team's favorite shows as kids.

18. The voiceover actors who play Betty and Vernon, the squabbling couple making the curbside "red zone/white zone" argument outside the terminal, are the real-life married couple who had recorded the same announcements at Los Angeles International airport. The dialogue, in which they argue over whether or not Betty should have an abortion, is taken from Hailey's original "Airport" novel.

19. Jimmie Walker ("Good Times") is one of the few comic actors to play a cameo. He's the filling station attendant who squeegees the plane's windshield and takes Capt. Oveur's credit card imprint.
20. The ZAZ team themselves have cameos in the film, as do several of their family members. The Zucker brothers are the ground crew at the beginning who accidentally cause a plane to crash through a terminal gate window. Abrahams is one of the religious fanatics Rex Kramer knocks over. Mom Charlotte Zucker is the passenger trying in vain to apply her makeup. The Zuckers' sister, Susan Breslau, plays a ticket agent. Abrahams' mother is the woman initially sitting next to Dr. Rumack.

21. Goofy closing credits have become a ZAZ trademark. Watch "Airplane!" all the way through, and along with the names of gaffers and grips, you'll see credits like, "Author of 'A Tale of Two Cities': Charles Dickens" and "Thirteenth President of the United States: Millard Fillmore."

22. The movie only cost $3.5 million to make. It earned back $83 million and was the fourth biggest hit of 1980.

23. Much of the cast returned for the inevitable "Airplane II: The Sequel," but ZAZ had nothing to do with writing or directing it.

24. In 2014, Delta Airlines issued an '80s-themed in-flight safety video that ended with a cameo by Abdul-Jabbar, back in the cockpit again.

25. Also in 2014, Hays and Abdul-Jabbar reprised their "Airplane!" roles for a TravelWisconsin.com tourism video, which included a reminder that the hoops legend used to play for the Milwaukee Bucks. Otto the Autopilot makes a cameo as well.