According to urban legend, a tornado hit a drive-in theater in Stoney Creek, Ontario, while this movie was playing. In reality, a tornado hit a drive-in theater in Thorold, Ontario, on May 20, 1996, damaging a screen. The movie was not playing when the tornado hit, but it was scheduled to play that evening.
The real town of Wakita, Oklahoma had part of its old downtown area demolished by the film crew for the scenes after the twister passes. The studio then paid for the downtown to be rebuilt. The town also kept the new fire truck used in the film.
The characters are alarmed when TV screens go blank, showing only static, before the tornado hits. In the days before digital TV, it was discovered that tornadoes generate a signal that will override and blank channel 2 on TV sets. Digital TVs do not react that way.
In order to get the background skies looking suitably stormy, the truck cab sequences had to be flooded with high-intensity lighting for contrast. As a result, Helen Hunt and Bill Paxton suffered minor retinal burns through much of the filming.
In an early scene when Philip Seymour Hoffman is sitting on a lawn chair, he lifts his leg in the air while laughing. His genitals were fully visible for a split second. It was edited out of the DVD and VHS releases, but it was leaked from VHS screeners sent to industry professionals.
Jan de Bont said he regretted thinking of the hail sequence because it took so long to do and was very difficult. Also the crew couldn't find ice blocks big enough in Oklahoma, so they had to find them in other states.
Many of the news reports spread throughout the movie are actual weathermen from Oklahoma news stations, including Gary England, chief meteorologist at KWTV in Oklahoma City, and Rick Mitchell, chief meteorologist at KOCO in Oklahoma City. The "1969" footage of Gary England giving the televised tornado warning to Jo's family is actual archived footage of him issuing a tornado warning; however, Gary England did not join KWTV until 1972.
Trailers contain a shot not in the film: a truck tire hurtling towards the viewer. This was supposedly one of the test shots that was created during pre-production to prove that CGI was capable of executing the effects sequences with the necessary level of realism.
After the team leaves Wakita, there is a seemingly impossible helicopter shot in which the camera descends several hundred feet in a matter of seconds, ending up mere feet from the convoy. This was achieved by having the cars drive slower than usual and then speeding up the film.
Jonas is vilified for selling out to 'corporate sponsors', which is ironic considering Pepsi's very prominent product placement. When the team is making the 'wings' for the sensors, all of the cans are Pepsi products. In almost all the shots showing the 'Doppler', the colors spiral inward and morph into the Pepsi symbol.
As stated earlier, the crew had trouble finding enough ice blocks for the hail making machine. Some were obtained from the Burlington Ice Company in Burlington, Iowa. The ice blocks were made special by pouring milk in with the water, so the hail would show up better on film.
Although Amblin Entertainment has collaborated with both Warner Bros. and Universal on many occasions (Amblin co-founder Steven Spielberg directed films for both studios), as of 2014, this film marks the only time Amblin collaborated with both studios on the same film.
The laptops used in the film are Silicon Graphics Indy Presenter LCD screens (not real laptops) that have been modified to look like functional laptops when in fact the screen image is generated by a computer off-screen.
The base camp (where the crew trucks and equipment are staged) for the end sequence was at a pig farm down the road from the well-house. Every morning the cast and crew were greeted by the smell of a 2-acre pig-waste holding pond in the middle of all the trucks.
The name on the tanker truck that pushes Bill's pickup off of the tree is "Benthic Petroleum" which is the same oil company that Ed Harris' crew works for in The Abyss (1989). Ed Harris majored in theater at the University of Oklahoma where the National Severe Storms Laboratory is located.
The original Director of Photography was Don Burgess (best known for his collaborations with Robert Zemeckis), but he and many other crewmembers walked off the set midway through filming after a series of heated arguments with director Jan de Bont.
As one of the characters looks at the screen of their weather computer, he screams "That's no moon, it's a space station!" That's Obi-Wan Kenobi's line when he, Luke, Han, and Chewbacca first discover the Death Star.
Six of the top 10 billed actors either starred or co-starred in 1 or more 80s cult classics. Helen Hunt-Girls Just Want To Have Fun, Project X, Peggy Sue Got Married, Next Of Kin Bill Paxton-Weird Science, Stripes, The Terminator, Next of Kin (played Helen Hunt's bro-n-law Cary Elwes-The Princess Bride, Glory Jami Gertz-The Lost Boys, Less Than Zero, Sixteen Candles, Crossroads Alan Ruck-Ferris Bueller's Day Off, Bad Boys (w Sean Penn) Todd Field-Gross Anatomy
The movie playing during the drive-in scene is The Shining (1980), directed by Stanley Kubrick. Todd Field, who plays Tim, would later play a major character in Eyes Wide Shut (1999), which was also directed by Stanley Kubrick.
The trivia items below may give away important plot points.
At the end of the movie Bill remarks that the tornado didn't take the house. In fact, it was originally supposed to. The Hardin County, Iowa, Historical Society and many citizens objected to the house being blown up so it was spared. The area is now a tourist attraction as the rubble from the barn and fences is still there exactly as it was in the movie.
There is a lot of speculation the Bill and Jo could not have survived being in the F-5 tornado at the end of the movie. While this would be true if the tornado was still at F-5 strength, as the tornado dissipated shortly after it hit them, the winds may have already been greatly reduced and the debris cloud lessened. So theoretically if that was the situation they could have survived as depicted.
At Meg's house Melissa questions about the possibility if exists a F5. Eventually she leaves Billy after a tornado destroys the drive in cinema, just before that Billy and Jo realize that a F5 is coming to happen, therefore she cannot see the F5 by asking.