Magic: The Gathering's Time Spiral block, whose set theme was nostalgia, is naturally full of Easter Eggs and other little jokes about cards from older sets. For example: in the flavor text of Viscid Lemures, Norin the Wary remarks that it's nice to face something harmless, like a lemur. On the (much) earlier Hyalopterous Lemure, the artist had apparently never heard of a "lemure", so the card is illustrated with a lemur.
The Lhurgoyf card had the flavour text "Ach! Hans, run! It's the Lhurgoyf!". Much later, a card with a similar power had the flavor text "Not again", attributed to Hans.
And in Time Spiral, Saffi Eriksdotter, who said the immortal line, became a card in her own right. Hans, unfortunately, did not survive to get his own.
That phrase also became an Unglued card◊. It summons a creature for one turn if the player says, "Ach Hans! Run, it's the..."
The card Deep Analysis has the flavor text "The specimen appears to be broken." The artifact being examined in the card's art is a Masticore, another card famous for being exceedingly powerful.
The card Persecute Artist doesn't let the caster choose Rebecca Guay. This is a nod to the time when rumors that Guay was being fired as a Magic card artist led to an Internet Backdraft.
The twelth editions print of Giant Spider states that "The wild is always changing, but it does have a few constants." This is probably a reference to the fact that by this point, Giant Spider was the only card that has been in all core sets since the game's beginning
A few cards in the Yu-Gi-Oh! Card Game are based upon storylines from the original manga from before the card game came to prominence:
Zombyra the Dark is based upon a character from a Show Within a Show Zombire, who is a Spawn Expy. Like Spawn, he gets closer to death the more he fights, represented by an ATK reduction.
Dark Master - Zork was the Big Bad of the Monster World story arc, which was a Table Top Game. From that comes the die-rolling effect, including the fact that a lower role is better and the highest roll is a fumble.
