It’s either in the chalice from the palace or the vessel with the pestle — or possibly, the flagon with the dragon. One of them has the brew that is true, but if you drink the wrong one? You’ve consumed the pellet with the poison and your goose is cooked.
Some of the funniest movie dialogue ever. This particular “bit” has been going through my head since yesterday. Enjoy. Have a laugh. You probably need one.