A revolver with a silencer attached to the barrel is fired several times in a scene. Almost all revolvers have a gap between the cylinder and barrel which allows gases and therefore noise out the side of the gun, rendering a suppressor useless.
However the revolver used in this scene is a Nagant M1895 which is one of the very few revolvers that can use a suppressor due to it's unique ammunition and gas seal system. When the hammer is cocked the cylinder cams forward onto a lip protruding from the back of the barrel. Additionally the ammunition used by this revolver has the projectile seated completely withing the case so the lip of the case forms a seal against the back of the barrel.