Question: Before leaving the plane, the doctor smirks, and after leaving he furtively looks back. He's supposedly an innocent, so why does he do this?
Question: In the scenes with the fighter jets flying besides the airliner, the fighters are depicted running with the afterburners (re-heat) on. This surely would not be the case for flying at a low speed of around Mach 0.8?
Answer: This is an error. The fighter jets depicted could easily keep pace with an airliner without the need for afterburners. However, this very well could be an intentional error. The sight of afterburners gives the audience a sense of high speed which heightens tension.
Question: How did the pilot get poisoned if no-one entered/left the cockpit?
Answer: From the Wikipedia entry for the film: "In the first-class lavatory, Marks discovers a hole drilled into the wall that offers a clear shot to the pilot's seat and discovers a dart in Wheeler's body."
Question: What exactly happened to the first pilot? Who killed him?
Answer: He was poisoned.
Answer: At no point is he shown smirking before leaving the plane. In the two shots he appears in before he is shown exiting, the first he is wearing an oxygen mask, and the second shows him straight-faced and helping someone to the front. The reason he looks back after going down the slide could simply just be to see who is coming behind him, or he could be examining the damage to the plane.
Phaneron ★