Trivia: When the 2015 Marty Jr. is walking across the street and a car stops, almost hitting him, he bangs both hands on the hood and yells, "Hey! I'm walkin' here!"I'm walkin' here!" This is an exact recreation of Dustin Hoffman's scene in 'Midnight Cowboy'.
Trivia: The Cafe 80's interior set is the same used for The Sting, when Johnny Hooker (Robert Redford) meets Doyle Lonnegan (Robert Shaw). It is located at the Universal Studios backlot in California.
Trivia: The 2002 DVD release of both this film and of Part III is very misframed, with many elements cropped out of frame or not centered properly. The most obvious example is when Doc demonstrates the adjusting sleeves on Marty's 2015 jacket (the sleeves are cropped out of the frame so that you can't see the effect), but nearly the entire movie is misframed. The disks were later reissued with corrected framing, and all later DVD and Blu-ray editions have correct framing.
Answer: He is attempting to play the song "The Power Of Love" by Huey Lewis and The News. He was first seen playing it very well in the first Back To The Future movie when he was trying out for the school dance. Jennifer recognizes the song and is shocked that Marty who was so good at guitar was suddenly able to hardly play it.