Vol.2 trailer
Go to the desktop, then quickly hold R1 + R2 and press Square, Triangle, Square, Triangle. Release R1 + R2, then hold L1 + L2 and press Right, Up, Right, Up. Release L1 + L2 and press R3 + L3. An option for "Vol.2 Preview" will be unlocked in the media player.

Bonus emails
Select the "Convert" option at the main menu. Convert the saved game files from .hack//Infection, .hack//Mutation or .hack//Outbreak to get an email from BlackRose that was sent to Kite after .hack//Quarantine. Convert a saved game file from .hack//Quarantine to also get that email in addition to an email from Hokuto sent to Rena. Note: In the Japanese version of the game, convert a saved game file from .hack//Fragment to unlock the email from Hokuto.

Alternate Tri-Edge name
If you converted a saved game file from the earlier . hack games when you fight Tri-Edge at the end, he will have the name of your character name from the earlier .hack game.

Free equipment from guild shops
To do this you must not be able to afford the item you want. You must, however, be able to afford at least one other item. You need to have enough GP so that if you used coupons on the desired item you would be able to afford it. First, start by selecting a buyable item as if you intended to purchase it. Then, add enough coupons so that if added towards the desired item, it would discount enough GP for you to afford it. Cancel the buy. Next, select the "unaffordable" item you want. It will appear as though you want to buy 0 of the item. Do not add coupons and confirm the buy. The item will no longer be in the shop inventory and will now be in yours. Note: If this trick is used on consumable items they will not be usable by you. Instead the consumable item purchased with the above method will only appear when using any shop's "Sell" option. You will have 0 of the item but will be able to sell only one, no matter how many times you "purchased" the consumable before going to the shop.