Factual error: After David's ship breaks free and exits the hangar, he orders Max to take him 20 miles away. Back at the tracking room a technician informs Dr. Faraday that the ship has gone 20 miles straight up, but the target altitude indicated on the screen reads 184,800 feet - more than a 35 mile distance. (00:52:00)
Factual error: When the alien craft speeds away from the NASA base, its slipstream tears off the roof of a small booth. But the wake also should sweep the people in its flight path down to the ground; it is too close for that not to happen.
Factual error: When the ship goes straight up 20 miles, the ship is in space with the curvature of the Earth and atmostphere visible. 20 miles is just over 100,000 feet. He would have to have gone over 50 miles up to reach space.
Answer: I can't directly answer this, but I was watching this movie just now, and didn't take in the girl at the beginning's (Jennifer's) name, so when Sarah Jessica Parker, Carolyn, appeared I then spent the rest of the movie assuming that she was going to turn out to be the girl he was crushing on in 1978, especially when Carolyn even told him he was cute (which is kind of a weird thing for a 20-year old to say to a 12-year-old if there isn't a plot reason for it). I do wonder if that was in fact the originally intended idea that was changed for whatever reason before the movie was completed, and if perhaps he was meant to go back to 1978 with the knowledge that she found him cute and therefore a new-found confidence to ask 12 year-old her out.
MrDannyDetail