Several shots of the aircraft carrier depicted it as having an angled flight deck, a technology that was not implemented until after the war, although no U.S. straight flight deck carriers exist anymore. While "Hornet" was portrayed by a World War II-era vessel (), "Hornet" was a (two members of the "Yorktown"-class were lost in the war and the survivor was scrapped), whereas "Lexington" was a modernized . The takeoff sequences for the Doolittle Raid were filmed on , a which did not enter service until 1961. As a supercarrier, "Constellation" has a much longer flight deck than the "Yorktown" or "Essex"-class carriers, giving the B-25s a substantially longer (and safer) takeoff run. The Japanese carriers are portrayed more correctly by comparison: and did have their bridge/conning tower superstructure on the port side rather than the more common starboard configuration. In the movie it was done by maneuvering an "Essex"-class aircraft carrier backward to act as "Akagi".