When Buck and Wayne are looking at their computer after their first sale in 1997, the blue and green task bar of Windows XP, which was not released until 2001, is clearly visible at the bottom of the screen.
Though set in 1997, when walking into the bar to meet the Russians for the first time, the car out side is a 2008 Ferrari f430. In 1997, a f355 would have been correct.
In the opening monologue, the teenager masturbating in the 1980s is wearing a Zoo York cap. The brand was only created in 1993.
In the car chase scene after the airport, they drive a 2010 Cadillac Escalade. The movie is set in 1997.
When Jack Harris (Luke Wilson) first meets Audrey Dawns (Laura Ramsey), she states her age as 24. In one of the later scenes in the movie with her and Jack Harris, a voice-over (long after the first meeting) refers to her as a "23 year old porn star".
Due to the frequent use of sunglasses throughout the film all sorts of equipment and crew can be seen in the reflection of the glasses.
Jack would certainly have his own attorneys from early in the movie, but he appears to act always and only on his own.
An internet billing company would not have scads of cash lying around, unless they were involved in other businesses not discussed in the movie.