For trivia relating to the games' parent franchise in general, click here.
- Cash Cow Franchise: Outside of being part of the massively popular Need for Speed franchise, the Underground games themselves were the among the most successful entries in the series, with the first Underground selling fifteen million copies and Underground 2 selling eleven million copies.
- Newbie Boom: It can be said that NFS received a large one when it shifted focus to tuners and aftermarket customization in the Underground games, during the early days of The Fast and the Furious franchise.
- Real Song Theme Tune: Underground has "Get Low" by Lil Jon & The Eastside Boyz featuring the Ying Yang Twins; Underground 2 has the "Fredwreck Remix" of The Doors' classic "Riders on the Storm", with special rap lyrics by Snoop Dogg.
- Unintentional Period Piece: Not just the typical kind from featuring the coolest cars of their time throughout the series' history, but Underground in particular is so painfully ingrained into early-to-mid 2000s with the tuner car culture with the bright neons, spinning rims, garish paint jobs, big sound systems in trunk, and whatnot, not to mention the awfully dated slang, that one may wonder why the hell was EA looking back towards them in the franchise's 2015 reboot (other than to capitalize on those jonesing for something akin to those past games). Plus, the original Underground had a song by Lostprophets in its soundtrack, something that would be flat-out inconceivable 10 years later (although, admittedly, Forza Horizon had it way worse). Underground 2 also prominently features the Cingular brand name and logo for the SMS. The Cingular name was phased out in favor of AT&T in 2007, setting the game firmly before that period.