Great post! The misspellings are certainly a mystery. QT writes his scripts long hand on pads, and I assume someone else types them up. That means whoever typed them was either error prone, or copied the mistakes directly from QT. And it's most likely the latter since anyone typing up QT's scripts better do it right.

Having read most recently Django Unchained, I can assure you that the spelling mistakes are due to carelessness. This isn't a shot at QTs skills as a dramatist, but as a proof-reader.