Originally Posted by
vivrant
The process is fairly simple Once you've booked your flight on any number of carriers that fly there (national airline:
http://www.cubana.cu/html/ingles/index.asp), and arrive at the airport, you will purchase a tourist visa for USD $15-$20. When passing through customs in Mexico/Canada/etc., they will stamp your tourist visa. Ditto for when leaving Cuba. You then present your US Passport when you arrive in Mexico/Canada/etc. This will ends up with you having two entry visas for that country (Mexico/Canada/etc.) but only one exit, but I imagine that if you have a enough stamps in your passport no one will notice.
It's a good possibility they wouldn't notice but it is possible. Once when I was leaving Philippines they neglected to stamp my passport. The Immigration officer in DTW noticed and asked about it. I told him I wasn't aware of it and asked, quite frankly, what he expected me to do about it. Of course he had to just say "Welcome back" and send me on my way. Point is, a missing stamp could potentially cause them to ask additional questions. In that case it would be foolish not to tell the truth, and admitting you had taken a trip to Cuba could cause even more questions.