When Hiro phones Ando and realizes he's talking to himself he hangs up and says "Gurehto Sukotto!" i.e. "Great Scott!", the favorite exclamation of Doc Brown, the inventor of the time machine in Back to the Future (1985).
At around 21:25 when Peter and Nathan are talking in the hospital, the lights reflected in the glass doors resemble solar eclipses.
The laptop given to Micah by his grandfather was purchased for the production of the show on eBay. It was worth approximately $1900 when it was new (which isn't far short of the $2000 stated by Micah's grandfather). However, AndoverCG Computer Liquidators, a company that provides specialized computer equipment for TV shows, bought it off eBay for $380. The laptop, in reality, does not actually work as it was sold for "parts."
Just before Niki/Jessica shows up at his house to confront him, Hal Sanders is reading "The Sirens of Titan," by Kurt Vonnegut.