Fail, I can't find the part that gives info on the free ticket (aside from the envelope).
Take a better picture of the letter where it states that and you'll have yourself an insanely popular reddit/imgur post on your hands.
"Proof the government thinks we're all fucking stupid (and that they're right)"
The instructions have sort of small lettering, but I'll post it anyway,
http://imgur.com/ys5tAnR,YRbbzxZ#0