The question is: who ate the rice-cake: you or the others? You construct the sentence differently in order to clarify the meaning.

Hey, the correct sentence should be: They also said that I pounded the rice cake that was kneaded by other guys and then ate it. I hope that's what you intended. But, it is also important to know that which part of the sentence do you wish to focus on?

If you put commas in becomes less confusing 1 ...., that the .....kneaded, and ate it ........you eat the cake 2 they..........and we ate it . 3 they.....and they ate it .