My first ever visit to the US was by driving from Vancouver to Seattle, no thought of incorrect visa and no probs getting in/out.
Did the Bahama's trip a few years ago and again no probs with visa's, the only potential problem for anyone wanting to take a US registered aircraft outside US territory is the "Tax" problem on the aircraft.
I flew with Dean Aviation" from Tamiami and they only had two C172's that were allowed to leave/enter the US, and then we had to climb to 3000+ to get a unique transponder code before crossing the "ADIZ" or be met then by a US interceptor.