That little boat was part of Task Unit Taffy 3. A small contingent of "escort class" vessels which fended off a Jap attack force comprising four battleships, including the Yamato, eight cruisers, and eleven destroyers. An amazing feat of daring, skill, and heroism.A quick Google search gave me historic context for why there are P-51 Mustangs on a carrier deck:
"P-51 Mustangs of the 506th FG aboard USS Kalinin Bay (CVE-68) being carried across the Pacific Ocean en route to Guam."