Inside the files of Wii Fit is an early model for the trainer who less resembles a mannequin and moreso appears to be distinctly white with blonde hair and almost fully realistic. The exceptions to this being her feet which have no toes, and her clothes that - while roughly the same color as the final character - are textureless (note that the attached image appears to be wearing a white onesie due to a rendering error). Based on the structure of the model and the full version of her body texture, it is apparent that the model was originally nude and the developers simply retextured parts of her body to create her clothing. The clothing meshes have their UV data removed, making them unable to use the body texture. The trainer also has a few unused animations of some warm-up stretches and yoga poses, but her shoulders get distorted and inverted due to how they are rigged. Additionally, while the warm-up poses flow together, the yoga poses (different steps of the Tree pose) are almost completely still and have no transition between them.

At the Seacroft Hospital in Leeds, England, physiotherapists have incorporated Wii Fit into their sessions with patients who have lost a limb and are learning to use a lower prosthetic limb. Senior physiotherapist Lynn Hirst states that many times patients have trouble "getting their weight through the prosthetic limb." However, with the aid of the balance board, Wii Fit allows patients to see "where they are taking their weight." Hirst stated that the Wii Fit therapy has been "absolutely fantastic" for all of her patients, and hopes that other Hospitals will follow suit with similar programs.

There are a large number of Mario sprites from the original Super Mario Bros. game hidden throughout Wuhu Island. These can be found during the running game.

Wuhu Island was originally created for Wii Sports before its debut appearance in Wii Fit. An early version of the island can be seen in a leaked development image for Wii Sports, and in footage of the unused Airplane sport in the E3 2006 demo for the game. The leaked image also indicates that the Airplane sport would have also given you the option to fly around the island with a Rocket Belt, an idea that would later be reused in Pilotwings Resort.