smoke trail of Air-Air Missile
When you fire an Air-Air Missile from a fighter that travels at an estimated 350-400 KIAS, then there will be a smoke trail from the missile motor BEHIND the fighter.
The smoke from the motor at launch will almost instantly slow down to near Zero speed, while the fighter continues to travel forward.
In the picture the smoke trail starts in front of the MIG - clearly a fake and a mistake by someone who never fired a missile in the air.