I show the entire breakdown of events from everything Marty said and did in front of George in 1955..... all leading up to 1985 (dates things were evented, and quirks Marty did). Think about it.... Who has an encounter with an alien from space?? And forgets they stated, they are Darth Vader from planet Vulcan. All pop culture George would come to witness... This kid is only around for a week in their lives, and keeps stalking George. George even yells at Marty at one point for always following him around... Darth Vader said he would melt his his brains if he didn't ask Lorraine to the dance. Marty only entered his life for a week, and kept pushing that too... Then vanished, once mission complete. In the first draft as shown in this video, George sees a news article of the dance, with Marty on stage, and figures it out. Never shown in the film. But it is quite obvious as shown in this video, he would have pieced it together.