(presentation) Custom Tracks

Here's my custom tracks thumbnail AND minimap

Bill Ball Cavern (FR: Caverne Bill Balle)
Minimap:
https://i.postimg.cc/44DN63cw/Bill-Cavern.png
Thumbnail:
https://i.postimg.cc/rF5yQLCT/Bill-Cavern-Thumbnail.png

Boo Lagoon: (FR: Lagon Boo)
Minimap:
https://i.postimg.cc/Pqjw2483/Boo-Lagoon.png
Thumbnail:
https://i.postimg.cc/8Cmr36R1/Boo-Lagoon-Thumbnail.png

Mario's Beach: (FR: Plage Mario)
Minimap:
https://i.postimg.cc/LXshb04T/Mario-s-Beach.png
Thumbnail:
No thumbnail created.

Bowser's Castle: (FR: Château de Bowser)
Minimap:
https://i.postimg.cc/t47dbF05/Bowser-s-Castle-1.png
Thumbnail:
https://i.postimg.cc/xTpH6qkb/Bowser-s-Castle-Thumbnail.png

Custom Tracks (FR: Circuits Custom)
Thumbnail:
https://i.postimg.cc/YS5td9sp/Custom-Tracks-Thumbnail.png

(For Mario's Beach I've got to download the race preview cause I deleted the track from my PC...)
There is a secret in Boo Lagoon! Try to find it and say where it is in the comments!
Look closely at the 2nd section in Bowser's Castle and you'll see something (it's clearly saying it right before)

This is the secret.

You found it!!!!1!1!1!1!1!1!1!1!1!1!1!!