This may be in Persona FES as well (it's the one edition of the game I don't own). For one of Elizabeth's quests, you need to get a portable game player from Junpei. Everyone who has already played knows that this is a reference to the PSP, as Junpei refers to it as the COMPstation Portable. However, if you take a second to look at the key items in your inventory, you will see that the item has an awesome description: "The 'Odin Cube' disc is already in the tray." 
 
Someone may have already pointed this out, but I just found it and it put a little smile on my face <3

It was in FES, I noticed it first there. I didn't even recognize it at first even though I had played a bit of Odin Sphere. Afterward I played it through completely, and added it to my list of great Atlus published games like Demon's Souls. Man... a portable version of Odin Sphere would rock, too. It would work so well on the PSP screen. And to think up until this year, I only owned 2 PSP games.

Another fun fact: A COMP is a device that has appeared a number of Megami Tensei games. In Shin Megami Tensei: Devil Survivor it resembles a Nintendo DS.