The Ancient Tongue which the Laguz characters speak is actually just a heavily stylized English font. The pieces of Ancient Tongue that appear on the game's menus can be translated, and when placed in order, form a quote from Shakespeare's Hamlet, specifically a love poem that Hamlet sends to Ophelia: "Doubt that the Stars are fire / Doubt that the Sun does not move / Doubt truth to be a liar, / But never doubt I love." The quote has no relevance to the game's plot, but is a neat reference to a famous line.
In the game's data are unused graphics of weapons and icons. These are all from the series's fifth entry, Fire Emblem: Thracia 776. The reason these are in the data is unknown, as they are never used in the game and would have no reason to be used.