This marks the first time Danny successfully used duplication. He first tried this power in "Maternal Instinct," only being able to split his head, then in "Reign Storm," when he was only able to accomplish it with the Ecto-Suit, and again in "Identity Crisis," to a horrifying result. This was the first time he was able to use it perfectly well unassisted.
"Torrent of Terror" is a pun referring to Vortex's weather-related powers, as "torrent" means a rushing stream of water or lava.
Even Though This Episode Premiered In 2007 It Was Made In 2006 According To The Credits