The Return of Hydro-Man: Part 1 - S5-E7
Other mistake: When Spider-Man catches up to Mary Jane and Hydro-Man at the foundry, he webs up Hydro-Man's left wrist. When the shot changes to Spider-Man landing, he is not holding onto the web-line. When the shot changes back to Hydro-Man, his arm his pulled with the web-line remaining taut, even though Spider-Man is not holding the web. If Hydro-Man was moving his arm on his own, then the web-line would be slack.