There were lines of gibberish written in the script for Leatherface. Tobe Hooper would sit with Gunnar Hansen and tell him what the lines meant, and the actor had to figure out a way to say that without actually speaking. In the scene where the Old Man comes home and starts yelling at Leatherface about the door, Hansen remembers a take where he communicated a little too verbally. Hooper told him "there was too much intelligence in the character," and the shot was redone. "My one chance to have a line," says Hansen.
Marilyn Burns, whose character was chased by Leatherface through the undergrowth, actually cut herself on the branches quite badly, so a lot of the blood on her body and clothes is real.
The soundtrack contains no sounds from musical instruments (with the exception of some copyrighted music they had the rights to), instead they used sounds an animal would hear inside a slaughterhouse.
Leatherface wore three different masks: the "Killing Mask," "Old Lady Mask" and "Pretty Woman Mask." Gunnar Hansen commented: "The reason he wore a mask, according to Tobe and Kim, was that the mask really determined his personality. Who he wanted to be that day determined what mask he put on. So when Drayton comes home with Sally, Leatherface is wearing the 'Old Lady Mask' and he's wearing an apron and carrying a wooden spoon, he wants to be domestic, helpful in the kitchen. At dinner he wears a different face, the 'Pretty Woman', which has makeup." The "Pretty Woman" outfit consists of a female wig and a black suit, as Leatherface is "dressing up" for dinner, an old deep south tradition which stems from his southern upbringing, and the "Killing Mask" is the skin mask he wears while chasing and murdering captives. Hansen later added, "The idea of the mask is that there is no personality under the mask. That was the idea in talking with Tobe and Kim. When they created the character, they said he has to put on masks to express himself because he himself can't do it. The way we tried to create him, there is nothing under the mask, which is what makes him so frightening."