- The entire story is told across novels, manga, television, and video games.
- As a special bonus for the fourth and final volume of the game series, Bee Train and CyberConnect2 (the companies who produced .hack//SIGN) created a bonus 29th episode entitled .hack//GIFT. In addition to a redesigned opening and a plot which features the characters from //SIGN and the games looking for a secret area called the Tasogare Onsen (Twilight Hot Springs), the episode contains radically different and cartoony designs for the characters that exaggerate their physical features.
- The opening sequence for .hack//GIFT is similar to that of .hack//SIGN, but with several differences: - Ucchi and Emy, two characters exclusive to //GIFT, appear in the "mouse click" scene. - Many times in the opening, Subaru, Bear, Mimiru, and BT flash between their //SIGN and //GIFT designs. Aura also does this in her floating scene. - During the scene in which Subaru, Bear, Mimiru, and BT wave their respective weapons and split in half, the //SIGN - version characters walk across, are briefly shown in their //GIFT forms as their bodies split, and immediately change back. - The "disintegrating clothes" scenes are replaced by ones of the //GIFT versions of Subaru, Bear, Mimiru, and BT floating against the tunnel of 1s and 0s. - Instead of the //SIGN Tsukasa being wrapped by the Guardian's tentacles, a //GIFT Tsukasa is shown being Data Drained. - When the dancing girl hits the water, she changes into the topless Helba shown in //GIFT, and the //SIGN Aura is replaced by her //GIFT counterpart.
- The ending sequence for .hack//GIFT features the //GIFT versions of the characters from //SIGN and the games in place of Subaru and Tsukasa walking across, respectively. At the end of the sequence, //GIFT versions of Subaru and Silver Knight are also shown.
- The character of Bear is inspired by Mel Gibson (I)' 's character in Braveheart.
- According to director Kôichi Mashimo the opening theme "Obsession" had to be written in English because in Japanese the lyrics would have been profane.
- Peter Cullen narrated the first promo created for the U.S. broadcast on Toonami.
- The series takes place in 2010 and only a few months before the story of the first game .hack//Osen kakudai vol. 1 (2002) (VG).
- Skeith's wand was redesigned slightly for the American release of this as well as for the American release of .hack//Osen kakudai vol. 1 (2002) (VG). In the original Skeith's wand is cross shaped while the redesign features a Q design.

