In one episode, Destro has to recite an ancient incantation to defeat a monster. If the incantation is recorded and played backwards, it says "Anyone listening to this message backwards is a real dweeb."
The line of action figures included one for Zartan the Swamp Master, a villain who was a master of disguise and who could camouflage himself like a chameleon. The action figure had photoreactive "skin" that would turn blue when exposed to direct sunlight, as did his vehicle. In the animated series, Zartan was allergic to sunlight and would be weakened when exposed to it, which also turned his skin blue. However, the figure was taken off the shelves late in 1986.
The premise was initially conceived by comic writer Larry Hama as Fury Force, which would have been an ongoing series for Marvel Comics. The original premise had the son of S.H.I.E.L.D director Nick Fury assembling a team of elite commandos to battle neo-Nazi terrorists Hydra. Though Marvel turned down the idea, Hama dusted it off when he learned that Hasbro was resurrecting their G.I. Joe toy line. Marvel issued a comic to help promote the toyline, and Sunbow's animated promotions for the comic paved the way for the ongoing cartoon.
Plans were made to have the character Rocky Balboa join the G.I. Joe team in 1987. In fact, Marvel Comics "G.I. Joe: Order of Battle" issue #2 contained a dossier for Balboa and Hasbro designed a prototype figure with Sylvester Stallone's likeness. Additionally, a new character, Big Boa, was added to the Cobra roster, complete with boxing gloves, to act as Rocky's Cobra counterpart and foil. A deal could not be reached to use Stallone's likeness, however, and Marvel wound up retracting the Balboa dossier, instead deciding on Sgt. Slaughter to be G.I. Joe's trainer and "celebrity spokesman".
At one point, Cobra was going to be Soviets, but this idea was dropped because it was considered culturally insensitive. Regardless, in "The Great Alaskan Land Rush," the Soviet counterpart to GI Joe, The October Guard, is an antagonist attempting to get an important seal in order for the USSR to reclaim Alaska.
Sergeant Slaughter, a real-life professional wrestler, became a member of the G.I. Joe team during the show's second season. The real Sgt. Slaughter provided the voice for the animated character. The animated Sgt. Slaughter remained a member of the G.I. Joe team in later seasons, even after his real-life counterpart became an anti-American "heel" wrestler, teaming up with an "Iraqi General," General Adnan, against Hulk Hogan at Wrestlemania VII during the time of the 1990 Persian Gulf War.
Real-life Chicago Bears football star William "The Refrigerator" Perry became a member of the G.I. Joe team in late 1986, with the codename "Fridge." A special edition action figure was issued, but "Fridge" was never featured on the animated series.