Ghost

Ghosts are a replay of a race in Time Trial. They can be seen in Crash Team Racing and Crash Nitro Kart.

Crash Team Racing
In Crash Team Racing, when you do Time Trial mode, you could Save your ghost. One ghost could be saved per game. If you do very good, you can race N. Tropy's ghost. If you beat his ghost, Oxide's ghost will replace him. Beating all of N. Tropy's ghost will unlock N. Tropy as a playable character, while beating Oxide's ghost will unlock  him and the Scrapbook.

Crash Nitro Kart
Ghosts return in Crash Nitro Kart. You can race a saved ghost, N. Tropy's ghost (after beating a certain time), or the real Velo's ghost (after beating N. Tropy). If you beat N. Tropy in all of the races, you will unlock him in Team Cortex. There is also a Lap Time Trial, where you are going for the best lap. After you complete a lap, your ghost will appear.