Mutagen Man Unleashed

Mutagen Man Unleashed is the 30th episode of the series and the 4th episode of the Second Season. It aired on November 9th, 2013.

Official Description
Donatello experiments with mutagen in an attempt to find a cure for April's mutated father.

Characters

 * Leonardo
 * Donatello
 * Raphael
 * Michelangelo
 * Master Splinter
 * April O' Neil
 * Casey Jones
 * Mutagen Man
 * Metalhead

Trivia

 * First appearance of Casey Jones.
 * Last appearance of Mutagen Man (even though he is still seen in the background in Donnie's Lab)
 * In the opening scene, The Turtles watch a show called SRMMF V, a parody/reference of 1980s anime such as Voltron: Defender of the Universe (aka Go-Lion) and the bad dubbing of anime from that era.
 * The mecha of the five heroes loosely resembles Voltes V from the anime of the same name, and the team's speech patterns resembles that of the Power Rangers. Their ridiculously long team name is a reference to Super Robot Monkey Team Hyper Force Go!, a show, executive producer Ciro Nieli previously worked on.
 * Like Space Heroes, SRMFF is used to foreshadow events for the episode or series.
 * When Casey is walking April to her apartment, you can see "Second Time Around" appearing in the background, which is April's shop in the TMNT comics, and the 2003 series.
 * When Raphael says to Donatello "As useless as a trench coat on a turtle" he was refering to the original 1987 series, where the turtles would simply wear a large trench coat and feel free to walk around in daylight perfectly disguised.