The Worlds are a reference to the Worlds in Mario games, and the Tower at the start of every level is a reference to the Tower at the end of every Super Mario Bros. level. Also, The Princess's Castle is a reference to Peach's Castle, while the Frog King's castle is a reference to Bowser's Castle.
The concept of a worm eating humans was probably inspired from the movie Tremors, where giant burrowing worms called Graboids kill/eat civilians.
The look of the giant worm looks almost identical to the Rishi Eel featured in the Star Wars the Clone Wars season one episode "Rookies". In the episode, while being attacked at their home base by the Separatist (the robots) the clones had to retreat to the caverns, there they were attacked by the Rishi Eel, a giant man eating worm.
Worm Food isn't the first flash game to resemble role of the player control a worm that eats humans in the following way.
In the Nitrome Jam-released game and upcoming mobile game 8bit Doves, a Game Boy appears on the title screen. On the mobile game, the corner of the screen reads "Nitrome Boy", and the graphics and music are a reference to games for the Game Boy.
Level 7 has a very similar level design to Flappy Bird.
The Nitrome Enjoyment System is a reference to the Nintendo NES.
The Nitrome.com avatar for Graveyard Shift's description, "the zombies are coming", is a reference to the video game Plants vs. Zombies, in which "the zombies are coming" is stated at the beginning of each level.