At the party Gilligan has more hair on his chest after he swings in than when he is in the tree.
When Gilligan comes swinging into the party as Tarzan, the first shot has him in control as he starts his swing, but the second shot of him has him out of control and on the upswing as he crashes into whatever was on the table, then in the third shot of him (on the same swing) he's in control and on the downswing again when he swings between the Skipper and Professor and into the hut's wall.
Mr. Howell drops the Skipper's invitation a few feet away from Skipper and Gilligan's hut. However, later when Gilligan stumbles and falls, he discovers the missing invitation. However, Gilligan is far from where all the huts are located. There is no way the invitation could have been wind blown way out into the jungle.