Was on AC1798 (YYZ-HAV) earlier this week.

CBSA was escorting a passenger onto the plane before everyone else. I assumed it was someone being deported or something. Upon arriving in Havana, the local gate agent informed the crew that the same passenger was being "refused entry."

What would happen in this circumstance? The plane has already landed and the passenger, refused or not, is sitting in Cuba. Obviously, the guy can't just sit there in the plane overnight (same plane returns as 1799 the next morning). Can AC be forced to fly someone back?