Hi,
That's covered by these rules (in the one-shot effects section of the Comp Rules):
610.3. Some one-shot effects cause an object to change zones “until” a specified event occurs. A second one-shot effect is created immediately after the specified event. This second one-shot effect returns the object to its previous zone.
610.3b An object returned to the battlefield this way returns under its owner’s control unless otherwise specified.
Carl is the owner of Flying Men, and since the Angel doesn't say otherwise, it will always return Flying Men to the battlefield under its owner's control (which is Carl), not the player who controlled it when it left the battlefield.
Nathan Long
Magic Rules NetRep