The player can save Ghosts, which are replays of Time Trials. The player can race against these ghosts on the track that the ghost was saved on. In Mario Kart 64, Ghosts were saved on Controller Paks. As such, ghosts can't be saved in the Virtual Console version of the game.
In Mario Kart Wii, if a player can defeat a first tier Staff Ghost they may unlock an expert staff ghost. These expert staff ghosts are the second and last tier of time-trial built in ghosts. Funky Kong and Baby Luigi are unlocked by defeating a certain amount of first tier ghosts, for Funky Kong you had to get 4 staff ghosts, for Baby Luigi, you had to get 8 staff ghosts, for Mii outfit B, you had to get ALL staff ghosts.
Often, the player starts out with three Mushrooms. However, in Super Mario Kart, the player starts out with none. Also in Mario Kart: Double Dash!! the player starts out with two, one for each character. Finally, in Mario Kart DS, the amount of Mushrooms the player starts out with depends on the Item stat of their kart, ranging from one to three. The mushrooms are used to speed up to get better results.