"Rigor Mormist" is a portmanteau word of "Rigor Mortis" which means "a recognizable sign of death where the muscles stiffen", and "Mist" which means "fog" which indicates the Fog Level.
"Graze The Roof" is a portmanteau word of "Graze" which means "to put" which probably indicates the fact that Bungee Zombies put down Ambush Zombies in Roof Level, or "to eat" which indicates the fact that zombies eat the plants, and "Raise The Roof" which means "to produce noise“.
"Grasswalk" is a portmanteau word of "Grass" which indicates the lawn grown with grass in the game, and "Cakewalk" which means "something that is extremely easy to do" which indicates that the Day Level is the easiest level in Adventure Mode.
"Loonboon" is a portmanteau word of "Loony" which means "a person who behaves in a strange way" which probably indicates zombies, and "Boon" which means "happy and cheerful" which fits the melody of the music.
"Cerebrawl" is a portmanteau word of "Cerebral" which means "relating to brain" which indicates that the purpose of the zombies is to eat brains, and "brawl" which means "fight".
Levels 1-10, 2-10, 3-10 and the Mini-gamesAir Raid and Column Like You See 'Em are the only to have a music piece called Ultimate Battle because 4-10 has no music played and 5-10 has a music called Braniac Maniac.
There is also an unreleased track called Zombotany. It was supposed to be played in the battles with Dr. Zomboss, until it was replaced with Brainiac Maniac.
Some parts of Zombotany appear to sound similar to Braniac Maniac, however.
There is an infrequent glitch that usually occurs on Pool levels, where the music will randomly change from Watery Graves to Grasswalk.
This also occurs with the Zen Garden on the DS version. It is unknown whether this occurs elswhere.
Loonboon was originally supposed to be twice as fast as it is currently.
The music in Plants vs. Zombies 2 is longer because unlike the first game, the music is not designed to loop.
In Plants vs. Zombies 2, most of the music are remixes of music from the first game. For example, the tutorial levels have a remix of Grasswalk, Ancient Egypt is possibly a remix of Cerebrawl, and Kung-Fu World is possibly a remix of the seed selection and Zen Garden music.
The only music played in Plants vs. Zombies that is not in a minor key is Zen Garden (C major). All others are in minor keys.