If you want to go to Cuba from the US, you need to fly to Canada and then to Cuba, as far as I'm aware. Also, our flight form Cuba back to Calgary was delayed for a day and a half so we had to sleep in the airport which was awesome! Customs seemed pretty lax, I managed to get drinks from the bar at our hotel and I'm like not even 18 or anything (I'm kind of a big kind of a big deal bitches). But ya, the airport had like bunkers and old helicopters right beside the runway which was pretty awesome, and they don't like Americans because you guys really fucked with them or something a long time ago and they haven't forgotten about that yet.
Tl;dr You can't fly there from the US, you have to fly out of Canada, there pretty chill and everybody's nice, and don't boast about being american because you will get raped.
If you're not building an atom bomb, you're a pussy.