Kart workshop

The kart workshop is a location that appears exclusively in The Super Mario Bros. Movie. It is located in the Jungle Kingdom, and is where Kongs construct and repair karts. The workshop notably features multiple booths where karts can be chosen (in a similar fashion to Mario Kart 7 and other Mario Kart games onwards) and built. The workshop also has an exit leading to the secret passage.

The Super Mario Bros. Movie
In the film, after Mario wins the battle against Donkey Kong in the Great Ring of Kong, Cranky Kong suggests that, to arrive in the Mushroom Kingdom before Bowser and his troops, they will need karts. He then takes Mario, Princess Peach and Toad down to the kart workshop and tells them to pick their karts. The three have done so and line up at the workshop's exit, along with Donkey Kong and the Kong army. When the group exit the workshop, it is never seen in the film again.