Factual error: The USS Hornet, a Yorktown-class aircraft carrier launched in 1940, is played by a much more modern Kitty Hawk-class carrier. The B-25s also take off from a steel deck instead of a historically accurate wooden deck.
Factual error: In the scene where the Japanese aircraft are launching for the attack on Pearl, an officer on one of the carriers holds a white flag in his right hand just as the planes are about to take off. Look carefully; the wind is blowing from the stern of the ship towards the bow (as evidenced by the position of the aircraft in the background). The flag should be moving in the opposite direction, as the carrier would be turned into the wind and moving forward at top speed to launch aircraft.
Factual error: During the attack on Pearl Harbor Danny and Rafe take off from an airfield and then fly to defend battleship row. As they fly over the harbor there are several Newport Class LSTs shown at anchor. This type of ship did not exist until 1966.
Factual error: When Ben Affleck is about to ditch his B-25 in China, and yells that the #1 engine is out, the port engine is shown spinning to a stop, with the propeller already feathered. A perfectly functioning engine would not have its propeller feathered; the pilot would feather it only after the engine stopped, to reduce drag.
Factual error: In the RAF squadron scene, the lined up Spitfires are the wrong mark for the period. For early 1941, the correct mark would have been a mark V. The Spitfires are later, as they have six exhaust outlets per side, and several have four-bladed propellers, neither feature being present on mark V Spitfires.
Answer: He is in the scene where the smaller air-base is being attacked by the Japanese. You have to look really closely but he is the driver of one of the jeeps right before the Japanese bomb drops (the one that seems to be a dud and then explodes). Also, Matt seems to be one of the gunners on one of the first ships at Pearl Harbor to return fire (this is not verified but in slo-mo, one of the gunners seems to be him).