Revealing mistake: A sign's wooden support gets shot at the beginning, but you can see where the pre-prepared weak point is in the support before it gets "shot."
Revealing mistake: Leatherface attacks the Mercedes. The pick up is driving backwards without the reversing lights coming on. Most likely a reversed shot.
Answer: It's basically Leatherface's version of an orgasm. Stretch appeals to his sexuality in order to survive, and he's aroused. He uses his chainsaw as a phallic object, rubbing it against her leg and then pressing it into her groin, and is panting, which obviously symbolizes his idea of sex. And then he becomes aggressive, revs up his chainsaw, and destroys the studio in an explosive emotional display, not unlike the strong physical/emotional sensation that comes with an orgasm. You could also theoretically make an argument that the mess he creates by sawing and throwing things around specifically represents male ejaculation, which involves a pulsating release of semen and can be, let's just say, "messy" sometimes depending on what sexual activity you're doing.
TedStixon
Thank you.
Rob245