If the referee must stop the game specifically for an injury, the restart is a drop ball. Whether the opposing team actually opposes this drop ball is not required.
Referees ball.
The referee will point to the center mark to indicate the restart; a kick-off.
Usually an injury to player whereby the referee stops play but doesn't give a free kick.
Since the goalie is the only one allowed to use their hands, they have different uniforms so the referee's can identify them for the other players.
According to the Laws of the Game, this would be sanctioned by cautioning the goalie and the player that switched and showing them both yellow cards.
So he can be distinguished from the rest of his players by, the players on the pitch, the referee and officials and the fans.
Everyone can touch the ball in soccer, but not with their arms or hands. Only the goalie can do that. The goalie can touch the ball with any part of their body. The referee can't touch the ball, or else that would mess up play.
It all depends on how you touch them, if the goalie has possession, and if the goalie is dribbling the soccer ball.
Referee!
A soccer goalie is not related to science. A soccer goalie is related to math because of all the angles he or she must cover.
If the referee deems it to be delaying the restart of play or unsporting behavior.
The same as any other player. The referee must be notified that the goal keeper is being changed.