Mrs. Pie, a character who appeared on the Rare website with Mr. Pants as part of the Pants family, was intended to appear in the game, but was ultimately left out.
Before choosing to base the game on Rare's mascot, Mr. Pants, other titles considered for the game were Splodge, Nutcracker, Animal Crackers and Sunflower.
Due to the childish nature of the drawings, Rare had the artists draw all of the game's artwork with their left hands so it would genuinely look bad.
The game was originally intended to have a multi-player mode with up to 4 players via a link cable, however the feature was dropped and the game became only single-player.
The gameplay was originally viewable in both 2D and isometric 3D layouts (whilst being developed as Donkey Kong Coconut Crackers), however there were consistency issues when switching between the layouts. It was also hard for players to see the board whilst in 3D and wasn't to the expectations of the developers.
It's Mr. Pants along with other Microsoft games were being developed for the Gizmondo handheld console, however they were canceled most likely due to the platform's commercial failure.
The "Crayon Snake" in marathon mode was originally intended to be called the "Trouser Snake", however the game's publisher, THQ, had requested for the name to be changed. This was possibly due to the sexual innuendo associated with the term.