Revealing mistake: When Dustin Hoffman dies at the end of the film, if you look closely at his chest you can see him breathing.
Revealing mistake: At the end on the bus ride to Miami, when Ratso Rizzo dies and Joe Buck uses his hand to close Ratso's eyes, Ratso's left eye flinches.
Answer: Coconut.
No, we see them trying to break the coconut (and failed miserably) after Ratso made that dish (and it looks like some kind of stew, probably made from the tomato we saw them steal at the same time they stole the coconut, and green peppers).