Oops, I should have been more clear. The 1cc/ml dose is of the baby gas products like Mylicon. Simethicone is not actually a drug, it is not absorbed by the body, so an overdose is unlikely. The theory is that it reduces gas by making the bubbles combine into bigger ones that are easier to pass (or something like that.) The simethicone itself simply passes through the digestive system, hopefully reducing gas pain along the way.
At BunnyFest this year, one of the audience people asked Dr. Harvey about simethicone, and she was lukewarm on using it. She said that bunnies do not get gas bubbles like humans do, and that she doubted that simethicone had any effect in the intestines of a rabbit. On the other hand, she said that there is no danger in using it, so she does not recommend using it or not using it. I have used it a few times on my bunnies, and it has worked a couple of times and not worked a couple of times. Who knows if the times that it did work, the bunnies would have come out of it on their own anyway.