Omg..
When i clicked the first Arnie, it screamed... Very loud.
By the way, i found 3 Arnies.. Lol.
For the first Arnie: It is when Mario walked out of the pipe, on the ground above with coins.
For Second: It is after Mario climbed the vine and jumped off. See him jumped into/onto a pipe where there is a Piranha Plant, where it just came out of the pipe, keep clicking until you can see Arnie. I did that..
For Third, it is when the credits came up, you have to right click with your mouse and click "Play" and it said..... Err, i don't know.... . And where is the button?
P.S: I speak bad english. Hope this helps...