Information on the location
Hill Valley is the hometown of Marty McFly and Doc Brown, as well as the main setting of the Back to the Future films. The movies have also shown past, future and alternate versions of the town. One of the most notable places in the town is the Courthouse Square, with the main building being the courthouse/clock tower, which plays an important part in the first movie. The clock in the tower is struck by lightning in 1955, resulting in the clock standing still from then on. The strike also generated the 1.21 gigawatts needed for the DeLorean to travel back to 1985.
The DeLorean is a time machine built by Doc Brown out of a DeLorean DMC-12, and it becomes his most successful invention. It is a plutonium-powered car (or by trash using the Mr. Fusion Reactor), needing 1.21 gigawatts of energy (either created by a nuclear reaction or a bolt of lightning), with 88 miles per hour of speed in order to time travel. In a later stadium, the DeLorean was also able to fly. It was eventually destroyed at the end of the third movie, but re-built by Doc Brown in the form of a locomotive.
Appearance in the rap battle
This is the location where Doc Brown rapped and where a Dalek and Marty McFly made their cameo apperances. The exact part of the town that is shown is the courthouse/clock tower, with the DeLorean time machine appearing in the background as well. It is also nighttime in the town and throughout the battle lightning can be seen flashing in the sky, similar to the climax of the first movie.