Title refers to the slogan often found on packaging of toy vehicles and play-sets to indicate the accessories that are included in the box. Usually also includes the line "action figures not included".
Skeletor says to He-Man "Let this be our final battle!". This is an homage to the Masters of the Universe (1987) movie where Skeletor says the same thing as he is powered up.
The symbol that lights up on the platform that Teela uses to access the lower chambers of Castle Greyskull is heavily inspired by the design found on the Mexica Sun Stone, also known as the Aztec Calendar, with a few modifications to fit the series lore.