Hole in One on Bugs Hole:
This is extremely difficult and may require use of the restart hole button a couple of times. To your immediate right, you see the large boulder with the foliage on top. Drive your putt up the stone, where a bee will take it and drop it in the hole.
It takes practice and the correct combo of aim+speed

Haunted House Hole:
To get a hole in one, hit the ball from the tee to the light grave on the left side of the house. If you do this correctly the ball will come out the back of the house.
This only works on the first shot.

Abominable Snowman Hole:
Putt into the middle tunnel for a hole in one.

Moon Base Hole:
Hit your ball into the metro station when the sign says 3.
If you don't time it correctly, the ball will fall intothe construction pit.

Jungle Hole:
Across from the pyramid with the hole there is a pool of water.
Putt your ball at the bird next to the water.
The bird will pick up the ball and drop it in the cup.

Volcano Hole:
On the Volcano hole, if you hit it hard at the smaller volcano to the left off the tee, the volcano will erupt and your ball will soar over the lava near the hole.