This card depicts text written in a mixture of Germanic runic alphabets, such as those of Futhark and Gothenburg, and it also features Mayan glyphs on its artwork. In Japan, the card's lexicon was published in the September 1999 issue of CoroCoro. The lexicon contained the complete translation of the card's runic text to both Japanese, in depth, and English, though briefly. It also presented the meanings of the four Mayan glyphs featured on the card's artwork — Enthronement (upper right), Heritage (lower right), Birth (upper left), Death (lower left) — together with a comprehensive sheet which deciphered the runes into phonetically-corresponding Latin alphabet letters. The card's illustrator is unknown due to its unusual design, though the issue showed Kouichi Ooyama impersonated as Dr. Mason from the Pokémon Trading Card Game.
People who attended a Wizards of the Coast event were given a sheet to read the runes. Based on this cheat sheet, the runes in the middle translate as New Species while the ones on the bottom translate as Little God... or Evil?. In the 2019 reprint the runes where changed and now can be translated as Little Good... or Evil?. Four symbols in the Holofoil printing behind Mew were said to stand for Birth, Enthronement, Right of Succession and Death. A method to decrypt the runes was also published on Pokémon.com, which referenced several other cards to determine what the card says. Due to this card's text being in Runic, this card is one of only two cards to have ever been banned from the Unlimited format in addition to the Standard format. It shares this distinction with _____'s Pikachu.
This card was depicted in The Power of One as the object that started Lawrence III's collection. The card was the only object from his collection still in his possession at the end of the movie. This was the second appearance of a TCG card in the anime, after the depiction of Dark Primeape in the Japanese version of EP073. No more TCG cards would appear in the anime until Pearls are a Spoink's Best Friend. In addition, the English dub had Lawrence III explicitly attributing the card as the start of his collection, in order to better tie in with the ending, as the pamphlet was not available with the American release. In addition, the card was originally meant to play a much bigger role in the movie, although it was largely excised from the film save for its brief appearance in the movie's ending, with Takeshi Shudo revealing the card's presence in the movie was a mistake.
The Weakness and Resistance symbols for Ancient Mew can be seen on the Xatu totem pole on the cover of the Neo Premium File 2.
Following the 2019 reprint of the card in Japan, that print and all prior prints became permitted to use in the Japanese Standard format starting July 26, 2019. Players using the card in sanctioned events were required to have a printed copy of the official card database entry detailing its text and place their deck in sleeves to make the card reverse indistinguishable from others.