The letter Clyde talks about writing to Henry Ford is actually a real letter and the quotes they say in the show are taken directly from the letter. However there is debate whether it was ever actually written by Clyde, due to the fake middle name of Champion when his middle name was actually Chestnut. He did however use the middle name Champion once when signing into a prison.
The $50,000 that Henry Ford was willing to pay for the gold key would be equivalent to $895,000 in 2016 after adjusting for inflation.
Rufus uses the name Wesley Snipes for his 1934 drivers license.