There is a hidden mickey on the Splash Mountain ride itself.  It’s not a classic hidden mickey, but a picture of Mickey riding Splash Mountain the ride.

You will find this hidden mickey at the end of the ride just as you are about to view your own picture from the large drop.  If you look to the left side of the log you will notice a portrait picture of Mickey Mouse riding Splash Mountain.  The picture is kind of angled so you have to look back to see it.

Here’s a picture of the Splash Mountain Hidden Mickey:

At the very beginning of the Splash Mountain entrance queue you will notice a sign.  The sign has a warning that you may get wet along with the normal safety and health precautions.  Go all the way up to the sign and look carefully at the woodwork of the sign.  You will notice a tiny knot that is in the shape of a classic hidden mickey.  You will not be able to notice it from far away so make sure you get close enough to examine the sign.

If you look closer you will find the knot of the classic hidden mickey.