I am pretty familiar with the movie - but I don't think they depicted any attack on any kind of CV - if I recall correctly the movie depicted successful attacks on numerous barges around Bataan, the sinking of a 'converted merchant cruiser', and culminated in the sinking of a Japanese CL (which was supposed to be a Mogami Class in the movie).
I checked the film ("They Were Expendable") and found two "mentions" of the sunken aircraft carrier: once on a shot of some sort of bulletin board (referred to as a "small aircraft carrier") and later when Lt Brinkley is trying to bum torpedoes from the Captain of an S-boat (referred to as "an auxiliary aircraft carrier").
I know that the PTs in the PI did not accomplish any great shakes but I sorta wonder if perhaps they did attack one of the IJN AVs at some point (a few of which are in the vicinity in WitP).