| Dwayne Johnson | Jack Bruno |
| AnnaSophia Robb | Sara |
| Alexander Ludwig | Seth |
| Carla Gugino | Dr. Alex Friedman |
| Ciarán Hinds | Henry Burke |
| Tom Everett Scott | Matheson |
| Chris Marquette | Pope |
| Billy Brown | Carson |
| Garry Marshall | Dr. Donald Harlan |
| Kim Richards | Tina |
| Ike Eisenmann | Sheriff Antony |
| Tom Woodruff Jr. | Siphon |
| Paul Darnell | Siphon (Stunt Double) |
| John Duff | Frank |
| Bob Koherr | Marty |
| Kevin Christy | Matt |
| Bob Clendenin | Lloyd |
| Sam Wolfson | Imperial Stormtrooper Ciardi |
| Bryan Fogel | Imperial Stormtrooper Gray |
| Robert Torti | Dominick |
| John Kassir | Chuck |
| Beth Kennedy | Stenftenagel |
| Jonathan Slavin | Gallagher |
| Harry S. Murphy | Analyst D. Pleasence |
| Ted Hartley | Four-Star General V. Lewton |
| Jack Eastland | General E. Albert |
| Meredith Salenger | Natalie Gann |
| Andrew Shaifer | Casey Taylor |
| Suzanne Krull | Gail Ross |
| Steve Rosenbaum | Oren Bergman |
| Christine Lakin | Sunday |
| Corri English | Herself (Brokedown Cadillac) |
| Randy Dunham | Himself (Brokedown Cadillac) |
| Don Ian | Himself (Brokedown Cadillac) |
| Jeff LeGore | Himself (Brokedown Cadillac) |
| Danny Reuland | Himself (Brokedown Cadillac) |
| Dave Engfer | Iscovich |
| Joseph Leo Bwarie | Frankie Valet |
| Omar J. Dorsey | Police Officer Hough (as Omar Dorsey) |
| Paul Nygro | Teddy Tentacles |
| Brandon Scott Miller | Hendricks (as Brandon Miller) |
| Andrew T. Janey | Repola |
| Dennis Hayden | Ray |
| Shengyi Huang | Shira the UFO Huntress |
| Hiromi Oshima | Fem-Alien #1 |
| Christina Wun | Fem-Alien #2 |
| Christopher Dobler | Hansen |
| Garrett Patrick Marshall | Bomback (as Garrett Marshall) |
| Buck | Junkyard |
| Hugh Daly | Black Ops Soldier (uncredited) |
| Stefán Mávi | Alien Larper (uncredited) |
| Delia Sheppard | Highroller (uncredited) |
| Pleasant Wayne | Bar Girl (uncredited) |
