LittleBigPlanet 4 has a wealth of unused audio files, such as unused voice clips, sound effects, ambience, and music. Some of these clips are technically used, but the entire file is not heard, while others are heard in unused levels or ultimately unused.
error.ogg will loop if a user attempts to launch the game after editing or removing a vital file in the game. It is the song 'Elevate This' by Kenneth Young looped over a black screen. This can be avoided by changing the value of "special" in the file "settings.xml" to "20-8-1-14-11 25-15-21 13-5-4-9-1 13-15-12-5-3-21-12-5 6-15-18 20-8-9-19 1-23-5-19-15-13-5 7-1-13-5 19-5-18-9-5-19".
ikazuchi.ogg is just under a minute long. The word "ikazuchi" appears to mean "thunder" in Japanese. It is found in a folder named "st_audio", which is also found in a folder named "st", which is sorted into the folder containing all of the sections. Along with it is a picture, which is strangely not placed under an image folder. These two files suggest there was a planned Japanese theme that had barely been started at all before being scrapped. The image can be seen here (presumably, this would be the picture appearing on the music box if the song was placed down).