Four Masters player Karl Lacey left the game in the 41st minute of the All-County League Division One clash.
County team-mate Gallagher was taken off by the Glenswilly management ten minutes later.
Lacey suffered a hamstring strain – while Gallagher had an ankle injury.
However both players are said to be fine after the match and will be ready for the All-Ireland final.
Four Masters won the match 2-11 to 1-09, with Donegal captain Michael Murphy missing a penalty in the clash in Donegal Town.