During the dinner scene towards the end of the film, when Leatherface cuts Sally's finger, he actually does cut her finger because they couldn't get the fake blood to come out of the tube behind the blade.
A family was actually living in the house that served as the Sawyer family house in the later half of the movie. They rented out their house to the film crew and continued to stay there during the entire shoot. During filming, the crew discovered that one of the residents had been cultivating a marijuana field; fearful that production would be shut down if they were found near the plants, the filmmakers called the Sheriff, who never arrived to investigate.
After getting into the old-age makeup, John Dugan decided that he did not ever want to go through the process again, meaning that all the scenes with him had to be filmed in the same session before he could take the makeup off. This entire process took about 36 hours (five of which which took to put the makeup on), during a brutal summer heat wave where the average temperature was over 100 degrees, with a large portion of it spent filming the dinner scene, with him wearing a heavy suit and necktie, sitting in a room filled with dead animals and rotting food with no air conditioning or electric fans. Everyone later recalled that the stench from the rotting food and people's body odor was so terrible that some crew members passed out or became sick from the smell. Edwin Neal who played the hitch-hiker claimed: "Filming that scene was the worst time of my life... and I had been in Vietnam, with people trying to kill me, so I guess that shows how bad it was."
Since the film's original release, the location used as the Sawyer family house has changed completely. It's now an open field, with no indication there had ever been a house there. The house itself has been relocated and fully restored. It is now operated as the Junction House Restaurant on the grounds of the Antlers Hotel complex at 1010 King Street in Kingsland, Texas.
Tobe Hooper allowed Gunnar Hansen to develop Leatherface as he saw fit, under his supervision. Hansen decided that Leatherface was mentally retarded and never learned to talk properly, so he went to a school for the mentally challenged and watched how they moved and listened to them talk to get a feel for the character.
Contrary to popular belief, this film is not a true story. It was filmed from 15 July 1973 - 14 August 1973, while the opening narrative claims that the real events took place on 18 August 1973, so it would be impossible for the film to be based on actual events which had not happened at the time of filming.
The film's original distributor was Bryanston Distribution Company, in fact a Mafia front operated by Louis "Butchie" Peraino, who used the movie to launder profits he made from Deep Throat (1972). In return, the production received only enough money to reimburse the investors and pay the cast and crew $405 a piece. The producers eventually discovered that Peraino had lied to them about the film's profits; after Peraino was arrested on obscenity charges when his role in Deep Throat was revealed, the cast and crew filed a suit against him and were awarded $25,000 each. New Line Cinema, which obtained the rights to "Chain Saw" from the bankrupt Bryanston, paid the cast and crew as part of the purchase agreement.
Gunnar Hansen said that, during filming, he didn't get along very well with Paul A. Partain, who played Franklin. A few years later, Hanson met Partain again and realized that Partain, a method actor, had simply chosen to stay in character even when not filming. The two remained good friends up until Partains' death.
Due to the low budget, Gunnar Hansen had only one shirt to wear as Leatherface. The shirt had been dyed, so it could not be washed; Hansen had to wear it for four straight weeks of filming in the hot and humid Texas summer. By the end of the shoot, no one wanted to stand hear Hansen or sit next to him during breaks to eat lunch because his clothing smelled so bad.
Even in his lift boots, Gunnar Hansen could run faster than Marilyn Burns, so he had to do random things when chasing her through the woods (you'll notice in one head-on shot that he starts slicing up tree branches in the background).
The close-up of Leatherface cutting his leg on the chainsaw was the very last shot to be filmed; the actor was wearing a metal plate over his leg, which was then covered with a piece of meat and a blood bag.
Tobe Hooper intended to make the movie for a "PG" rating, by keeping violence moderate and language mild, but despite cutting and repeated submissions, the Ratings Board insisted on the "R" rating for the effectiveness of what is onscreen and what is implied offscreen. Hooper had a similar ratings problem with the sequel.
Some urban legends say that the the "real" Texas Chainsaw Massacre took place near Poth, (a small town about 36 miles southeast of San Antonio. This is false. The film is fictional and based loosely on the life of Wisconsin serial killer Ed Gein (as is the classic Psycho (1960)).
A still photo taken during filming of the entire 'Sawyer' family posing outside the house as a gag was found and stolen from the set by a visiting German reporter who took it back to West Germany with him, and the image of the family eventually became the advertising poster for the first release of the movie in West Germany.
Gunnar Hansen hit his head on doorways and other objects several times during the shoot because the Leatherface mask severely limited his peripheral vision and the three-inch heels he wore made his 6'4" frame too high to clear all obstacles.
This film has had a long and troubled "relationship" with German law. The original theatrical version in West Germany was denied a rating and therefore cut. In 1982, the film was put on the index for youth-endangering media. Then in 1985, the film was banished by the Munich district court and all existing copies were confiscated. Over the years the film was released on VHS and DVD in various (legal and illegal) versions, mostly cut. Since April 2008, the new German licensee, Turbine Medien, has tried to get the banishment revoked and the film removed from the index. Only in September 2011, the district court of Frankfurt/Main finally lifted the banishment of the film (it is the first time in Germany that such an attempt was successful, making judiciary history). Finally, in December 2011 the film was removed from the BPjM index and subsequently rated "Not under 18" by the FSK.
The film was rejected by the British film censors in 1975, but it did get a limited cinema release in the London area thanks to the GLC (Greater London Council). It was banned again in 1977, when the censors' attempts to cut it were unsuccessful, (for the purposes of a wider release), then it was banned again in 1984, due to the growing controversy involving 'video nasties'. In 1999, after the censors finally changed their policy, they took the plunge, and passed it uncut, for the cinema and video, after 25 years, since they first banned it.
The film's original budget was $60,000; during the editing process, the filmmakers amassed an additional $80,000 in costs, requiring that they sell off portions of their ownership in the film's royalties.
The company worked seven days a week, 16 hours a day, in the summertime in one of Texas' notoriously brutal heat waves where the daytime temperature was over 100 degrees and later hovered at around 80 at night.