Interesting side note: those are American made helicopters.
Images via Khaled Desouki/AFP/Getty Images
"The first time we see Marty McFly, he visits Emmett “Doc” Brown’s home and discovers a mess of dog food. He then proceeds to play one note on his guitar using Doc’s giant amplifier. The sound knocks Marty across the room. Doc calls right after that and gives Marty some instructions for later.
The last time we see Marty, he and his girlfriend Jennifer Parker visit the site of the mess that used to be a DeLorean. They are blown backwards by an incoming train Doc has turned into a time machine. Doc then shares some wisdom with Marty and Jennifer to help them in the future.”