Donkey Kong 64 Easter Egg - The Dolphin, Earlier DK Games References

At the very start of the game, look around DK's cabin to see bits and pieces from his previous adventures (including girders, the grammophone and stereo from Donkey Kong Country etc.) On one wall is a picture of a dolphin. This is one of the earliest references to the Gamecube's codename at the time - the "Dolphin".