The now-infamous fight in which Cap kills Baron Blood in the 616 universe went wrong in the other universe shown in Exiles. Cap had a tear in the neck of his costume, so instead of Baron Blood's fangs being turned by the chainmail the way they were in the 616 universe, Blood managed to bite Cap and turn him into a vampire.
One of my favorite Exiles realities was the one where Warlock's race had basically turned Earth into a technological collective by infecting most of the world's heroes with their techno-organic plague. I liked that Sunfire got to be happy with the lesbo MJ/Spidey and that the Asgardians ended up saving the day.