I am not sure whether I posted this earlier or not, because I remember this glitch from earlier.
When the ghost car is switched OFF and is not visible on the track in Time Trial, "it" still leaves water splashes wherever it drove through water, even though the ghost can't be seen, only the splash appears.
Here on the left, the splash comes from an OFF ghost car that drove through the water pond.
Ghost car leaves splash even if switched off
Re: Ghost car leaves splash even if switched off
You really can say it's a ghost car