Complex sentence: Joy and Bing Bong then seek out Bing Bong's discarded song-powered wagon in order to escape, but after several failed attempts, Bing Bong realizes their combined weight is too much, so he jumps out to allow Joy to escape and fades away.
Split into simpler sentences: Joy and Bing Bong then seek out Bing Bong's discarded song-powered wagon to escape, but after several failed attempts, Bing Bong realizes their combined weight is too much. On a final attempt, he jumps out to allow Joy to escape and fades away.