The voice script for Mario Teaches Typing contained multiple negative remarks towards the player such as "That wasn't very good" and "That was a failure". Voice actor Charles Martinet objected to these remarks, and was given permission to write his own, more supportive lines such as "That was great, but you can do even better!" and "Great try!"

Charles Martinet, the voice actor for Mario from 1990 to 2023, first officially voiced the character as part of a motion-capture Silicon Graphics interactive exhibition used at Nintendo trade shows (with the role at the time sometimes split between him and musician Steve Coyle). The first commercially-released product to feature his voice acting is purported to be the Super Mario Bros. pinball machine released in 1992 and produced by Gottlieb. According to Martinet when asked by a fan in 2018, Gottlieb "stole" his voice clips and did not credit or pay him for his acting. While the 1995 PC game Mario's Game Gallery is often cited as Martinet's first official role as Mario in a video game, the actual first credited video game to feature him as Mario is the 1994 PC educational title Mario Teaches Typing, where he replaced the DOS version's voice actor, Ronald B. Ruben.

An early unused sprite of Mario jumping can be found in the game's data. He has different shading and his arm is bent differently.

Within the hex code of the game's EXE file is ASCII art of Mario's head.