One of the commands Milo enters when accessing the surveillance system in the day-care center is "show -p 1984", this is a reference to George Orwell's book "1984" which describes a completely controlled society where everyone is monitored by the government.
President of NURV Gary Winston appears to be an amalgam of the CEOs of Microsoft and Apple: Bill Gates and Steve Jobs, respectively. NURV resembles Microsoft in power and composition, and Winston's appearance is modeled after Gates. But Gary Winston also posesses Steve Jobs' cutthroat business drive, fiery temper, and motivational speeches. This combination is also possibly supported by the coexistence of both PCs and Apple computers on the NURV compound
The code shown in the first visible screen (skipping the intro sequence) is a section from a real compression scheme, named bzip2, which is Free Software. The remaining sections of code in the movie, almost exclusively, come from a web server named Jigsaw, also available as open-source.
During the sequence where we are shown the "open source" developers that are monitored by NURV you can clearly see one of them wearing a red hat which looks exactly like the one that the company Red Hat uses as their logo. Red Hat is a GNU/Linux distribution.
Three of Winston's thugs have the last names Schmeichel, Sheringham and Solskjaer. This is a reference to the goalkeeper and goal scorers on Manchester United's 1999 U.E.F.A. Champions League winning team. The director is a Man. U fan.
The jacket number (and reference in the NURV computer database) for Richard Roundtree's character, Lyle Burton, is ND47. The number 47 occurs frequently in science fiction (most notably in Star Trek) due to a "joke proof" written by Donald Bentley in 1964, showing all numbers to be equal to 47.
The first time Gary comes up to Milo with "helpful code," there is a glimpse of the source. If you look closely at the byte casting in the if/else statement it vertically reads "GET "..."HEAD ". Followed immediately by Gary's statement. "Oh God. Oh, so much fun. I love doing this."
The keyboard Milo uses in the day care center is an Apple USB Keyboard, as used on Macintosh computers. In addition, the operating system used on the computers in the day care center is a form of Unix, as shown by the command prompt. The Unix commands Milo uses are largely accurate, as well. Apple is ultimately vindicated in the end when the good guys are handling the Synapse broadcast from a Macintosh PowerBook G3.
When Phil's buddy is spying off the code someone is creating, and seeing what his computer says should be the correct code, the new code recommendations have a typo in them (MessageBox(hDlg, "You've not enouph space on disk",). Enough is spelled as enouph. This is 54 minutes into the movie.