Big Time Rush and Victoria Justice performed for a whopping 28,000 Rushers in Mexico City, and it was an adventure. There were costumes, duets, mobs of fans and a ton of fun -- and much of it was caught on camera!

Big Time Rush took a slew of photos of the enormous crowd when they weren't too busy being silly with Justice and opener Olivia Somerlyn. They joined Somerlyn onstage for 'Better With You' and sang with Justice for her song 'Shake,' and she later returned the favor ... wearing a banana costume!

Justice wasn't the only guest during 'Time of Your Life.' Carlos Pena, Jr.'s real life girlfriend, Alexa Vega, came out to applause and cheers during their performance as well!

Our favorite video, though, is one of the bands and crew lip syncing to AC/DC's 'Thunderstruck.' See it all here!

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Watch Big Time Rush + Olivia Somerlyn Perform 'Better With You'

Watch Big Time Rush + Victoria Justice Perform 'Shake'

Watch Victoria Justice Come Onstage in a Banana Costume

Watch Alexa Vega Come Onstage During 'Time of Your Life'