In the beginning, in the treehouse scene, when Vern first asks if the guys "want to see a dead body?" Notice that before he says it, Gordies hair is messy and in his face, yet after he says it, Gordies hair is gelled and combed back.

Also, in the famous leech scene, as Chris, Teddy and Vern are involved in the 'water fight,' Gordie tries to sneak by, as he walks by notice that his hair has completly dried from having fallen underwater not 15 seconds before. But then its wet again.