The Turtle's rival group of ninjas, "The Foot", are a tongue-in-cheek reference to the extremely popular four issue Wolverine limited series by Frank Miller and Chris Claremont. In that series, which had just been published when the Ninja Turtles first appeared, Wolverine was constantly dealing with a group of ninjas called "The Hand".
Despite The Shredder being the arch villain bent on destroying Splinter and the turtles and sometimes attempting to be a ruthless conquerer, his biggest interest had always been to be a writer. In fact, he has been heard using creative and clever sentences to his pleasure.
For Season 4, 28 episodes were produced for syndication and 26 episodes were produced for CBS' "Kid TV" Saturday morning line up. However, 15 of the syndicated episodes never aired in 1990. The "European Vacation" episodes were not seen in the United States until USA Network started showing reruns in late 1993, and the "Awesome Easter" episodes weren't seen until 1991. An easy way to tell that these are Season 4 episodes is: the original intro is used, title cards are used, the closing credits uses the still image that debut that season, and the Technodrome is stuck on an asteroid in Dimension X. The most likely these episodes were delayed was because of animation or schedule problems.
In the original Mirage comic books, the Foot Soldiers are real people, not robots. As such, the comics showed the turtles killing Foot Soldiers in fight scenes. For obvious reasons (issues of violence in children programs), the soldiers were changed to robots and the turtles are never seen killing anyone despite their use of offensive weapons.
When the show aired on CBS, many Public Service Announcements aired on CBS Saturday Morning line up. These PSA's were called "Turtle Tips" and intended to benefit the public interest, by raising awareness of environmental issues.
In many of the newer episodes, Michaelangelo used a grappling hook as his weapon instead of his traditional nunchucks. This is because nunchucks were outlawed in many countries, due to Bruce Lee's The Chinese Connection (1972), and since the show went international, they changed it for everyone.
Like other cartoon series built around an action premise, TMNT did not escape criticism by parent groups for its violence. In the case of this series, schools began reporting that children began getting into fights during recess and seriously hurting one another in an attempt to mimic the martial arts moves depicted in the show.
Creators/producers Kevin Eastman and Peter Laird wanted the series to be dark and dramatic like their comic book on which the series is based. But the voice actors would have so much fun recording together that they played up the comedic aspects of their characters. Also, most of the voice cast had young children and they wanted them to be able to enjoy the show.
In the comics, movies and other ninja turtles TV shows, the turtles are often referred to as abbreviated versions of their names Leonardo-Leo Raphael-Raph Donatello- Donny Michelangelo- Mikey. In this series, they are always referred to in full context.
Lotus Blossom bares a resemblance to Karai from the original comics. Which lead fans to believe that she is an alternate animated counterpart to Karai. Despite popular belief Lotus actually first appeared on the show three years before Karai was introduced in the comics.