This monster appears in the artwork of "Ancient Rules", which is referenced in this card's flavor text.
Its Level and its ATK are also referenced in this card's flavor text.
As "Ancient Rules" was released nearly six years prior to this card, "Wattaildragon" is one of the only Monsters in the game to debut on a Spell or Trap, then only later become a Monster. It shares this distinction with "Warrior of Zera", who first appeared in "Zera Ritual".
The hilt on "Warrior of Zera's" sword also bears a slight resemblance to the head of "Waittaildragon".
The art and flavor text of "Waittaildragon" are similar to DRUMP, a 2013 one-shot manga by Kazuki Takahashi about a blue dragon imprisoned inside a deck of magical playing cards for thousands of years.
This monster is the first "Watt" monster that isn't a Thunder-type monster, the second "Watt" Normal Monster (after "Wattkid"), and the strongest "Watt" monster in terms of ATK.