An edited version of "Born Too Slow" was featured in the soundtrack for the video games Need for Speed: Underground and Donkey Konga 2. The song "I Know It's You" was used in the pilot episode of the TV show Numbers. Also, the song "Bound Too Long" was featured on the soundtrack to the movie Cursed, and "Starting Over" was used in an episode of the TV show Alias and an episode of CSI: Crime Scene Investigation. "Weapons of Mass Distortion" was featured in the teaser and theatrical trailers of The Bourne Ultimatum and a different version of the same song, renamed "Weapons of Mad Distortion" was used in the film Blade: Trinity.
The album also contains the only known time either members of The Crystal Method have provided vocals for a song. The song that features this is "I Know It's You", which has Ken Jordan singing through a vocoder.
Upon release, Legion of Boom received mixed reviews from critics. The album has a score of 58 out of 100 from Metacritic based on "mixed or average reviews".Billboard gave it a mixed review and stated that "Too many tracks get bogged down with a straight-ahead progressive trance formula, where zoning out feels more suitable than attempting to move your feet. Still, because the good stuff is so darn good (and it is), it is easy to brush aside any missteps."Mojo gave it three stars out of five and said it was "more like the soundtrack to a horror movie than a night of DJ breaks and body shakes."Playlouder gave it two stars out of five and said the album "resembles nothing more than a U.S. major label executive’s idea of what dance music should sound like."URB also gave it two stars and said that the band "has become utterly irrelevant."Blender gave it one-and-a-half stars out of five and stated: "The problem is not the lumbering, mid-tempo beats or the terrible lyrics (“Synthesizer, crystallizer, realizer”), although neither help. It’s the sense that you’ve heard every synthesized squelch and ambient breakdown before."