End of Game Freeze
It is possible to have your game freeze as you finish fighting the Act II final boss. When this occurs, portraits will become glitched, and the game will freeze during the credits. You will have to hard reset, and progress you made since your last save will be lost.
Known Workarounds: Go to your settings and turn off portraits, BGM, SFX, and do not bring anyone with you to the final battle. This will greatly reduce your risk of encountering the glitch. Failing to do this does not guarantee you will encounter the glitch, but if your game freezes once then you should do this on your second attempt.
At random, the game graphics may glitch. Portraits will usually become bugged first, followed by sprites and scenery. The exact triggers are unknown, but this is an uncommon bug.
Repeat Boss Battles
Although you get Prince Points and boss drops appear when a boss monster vanishes, the barrier around a boss room will linger for a second longer, and the game does not consider the boss battle completed until the barrier disappears. If you warp out of the room before this happens, you can fight a boss multiple times a day. 
Game sometimes or frequently locks up during normal play. The most common culprit is using fully range-extended weapons that can inflict all status ailments on a large crowd of enemies.
Character portraits and occasionally other graphics will have blue lined bars running through them. Often occurs as a result of too much soft-resetting, and can generally be triggered on Beach Day by hanging around Dragon Lake all day long without leaving the screen.
During the Fishing Frenzy Contest, it is possible to come across a line where Margaret speaks in Japanese. All she says is Forte's name. One random traveler also has an untranslated line of dialogue.
If you throw a piece of furniture that is capable of storing items, then throw a storable item at it before it has finished bouncing, the furniture will float away. You can still interact with the furniture by inspecting the space where it is supposed to be, and if you leave the room and come back, the furniture will have returned.
Some field and barn names will revert to default upon reseting or reloading the game.
The Senility of Volkanon
He can abruptly begin referring to Frey as "Sir" rather than "Miss."
Don't Do It!
Characters can sometimes be found standing in places such as on the palace roof, on top of furniture, or stuck in the cliff at Dragon Lake.
Dylas will sometimes display a sad portrait when he should be blushing. May be caused by soft-resetting.
Luna and Noel can abruptly start referring to Frey or Lest by their first name. They can also randomly address Frey as "Daddy" in their voice clips.
Valentine's Day Confusion
Females, usually bachelorettes, sometimes react to Frey as a boy on Valentine's Day and cease presenting them as a "friendship cookie."