The jettison nozzle on the 744 is outboard of the engines , and I believe that they also have a flame arrestor in them so that a flame is unable to travel into the fuel system.
FYI, fuel tank vents also have flame arrestors in the wing tips and the hori stab. And the centre tank scavenge pick ups were also modded a few years back and arrestors installed. I think they were a band aid fix after the TWA 747 blew up of the U.S coast.