2151, of course, was the year the first Starship Enterprise was launched (in the "Star Trek: Enterprise" series).
TRANSCRIPTION COURTESY OF JOSEPH HOUK - [Dallas area park; two guys are talking over a photo of a certain time-traveling DeLorean] (Guy 1, holding an iPad) "It's almost 2015. Shouldn't we have those flying cars by now?" (Guy 2) "Yeah, I want my hoverboard! What the hell, people?" (BG) "I bet you get tired of hearing that, huh?" (CW) "As popular as 'Back To The Future' has been, we better get used to it!" (BG) "Are we always gonna have those snide comments about what's failed to show up when it's supposed to?" (CW, activating her time machine) "Well, let's find out, shall we?" [2150; the two arrive in the future Metroplex overhearing two other guys talking over a holoprojection of… the USS Enterprise!] (Future Guy 1) "It's almost 2151. Shouldn't we have the Starship Enterprise by now?" (Future Guy 2, wearing a "Garthritis" t-shirt) "Yeah, I want my Vulcans! What the glurtz, people?"