Flight 136 is shown to be a DC-10 from the exterior shots and reference from a character. The interior of the cabin and the flight deck is clearly that of a 747. The flight deck has four throttle levers and four sets of engine instruments versus the DC-10's three. The forward end of the cabin curves sharply in as does a 747 and the inside of the exit doors match a 747.
When the hijackers take over we see three flight attendants brought to the coach section, along with the two attendants already stationed in there that makes five. There would be upwards of 10 on a DC10 passenger flight.