Darkness and Light: Part 1 - S1-E11
Other mistake: The river that Hulk battles Doc Samson in is only ankle-deep, but when Samson knocks Hulk out with the sonic gun, the river current is able to carry Hulk downstream. Hulk is lying flat on his back, and since the water is only ankle-deep, his back would be touching the floor of the river. In this case, the current of a shallow river would not be able to carry someone of the Hulk's mass.