In the beginning, while landing at Dulles, the Concorde makes a steep turn aligning with the runway. In real life, even a small, relatively slow plane (like a Cessna) needs a few miles to approach a runway.
A magnesium-based flare would burn until it ran out of fuel. To put it out requires a fire extinguisher capable of handling burning metal. Those types of extinguishers are not carried in an airplane cockpit.
Capt. Joe Patroni: Goddamnn! He fired one! Missiles at five o'clock! Those missiles have a narrow seeking angle, no more than thirty degrees. If we make enough violent maneuvers we may be able to cause a fly-by. Son of a bitch!