The Griswolds head off for Las Vegas, as Clark got an extra bonus for developing a food preservative. In the city of fortune, the family ties are once again tested by forces of nature: Ellen finds herself tempted by Wayne Newton, Clark manages to lose all the money the Griswolds own, Rusty, not being 21 years of age yet, hits a lucky streak as Mr. Pappagiorgio and Audrey teams up with Cousin Eddie's daughter Vickie to dance at very interesting night clubs. Also, the Griswolds nearly cause the breaking of Hoover Dam, Clark meets some of Siegfried and Roy's white tigers up close and Cousin Eddie, who now owns some land right out of Las Vegas, gladly offers his helping hand. But the feeling of love and family will bring them all back together again, be it richer or poorer than before - what does money matter anyway?
| Chevy Chase | Clark Wilhelm Griswold, Jr. |
| Beverly D'Angelo | Ellen Priscilla Ruth Smith Griswold |
| Randy Quaid | Cousin Eddie |
| Ethan Embry | Russell 'Rusty' Griswold |
| Marisol Nichols | Audrey Griswold |
| Miriam Flynn | Cousin Catherine |
| Shae D'Lyn | Cousin Vicki |
| Wayne Newton | Himself |
| Siegfried Fischbacher | Himself (as Siegfried) |
| Roy Horn | Himself (as Roy) |
| Roy | Himself |
| Wallace Shawn | Marty |
| Sid Caesar | Mr. Ellis |
| Julio Oscar Mechoso | Limo Driver |
| Sly Smith | Mirage Security Guard |
| Julia Sweeney | Mirage Reception Person |
| Corinna Harney | Girl at Blackjack Table (as Corinna Harney Jones) |
| Joe Armeno | Roulette Stickman |
| Christie Brinkley | Woman in Ferrari |
| Juliette Brewer | Cousin Ruby Sue |
| Zach Moyes | Cousin Denny |
| John Finnegan | Arty, the Hoover Dam Guide |
| Seth T. Walker | Bellman (as Seth Walker) |
| Howard Platt | Maitre D' |
| Elizabeth Illia | Woman at Concert |
| Wayne Brown | Croupier |
| Maria Cina | Mirage Cashier |
| Wendy Kaufman | Wendy |
| Joe Lacoco | Riviera Bartender |
| David L. Garoutte | Riviera Security Guard |
| C.C. Costigan | Kelli |
| Peter George | Marcus |
| Frank Mendonga | Kurt |
| Daniel Steven Lopez | Kyle |
| Shannah Laumeister | Mariah |
| Aki | Aki |
| Bud Ekins | O'Shea Security Guard |
| Gary Devaney | Croupier #2 |
| Jerry Weintraub | Jilly |
| Bernie Yuman | Doc Sandy |
| Paul Kessler | Silent Al |
| S.A. Griffin | Pit Boss |
| Lou DiMaggio | Casino Host |
| Ruth Gillis | Saleswoman |
| Samuel J. Marber | painter |
| Antonio Mitchell | Larry |
| Jason Stuart | Buffet Guy |
| Nick Mazzola | War Dealer |
| James Migliore | Rock Paper Scissors Dealer |
| Reno Nichols | Coin Tosser |
| Frank Washko Jr. | Guess Which Hand Dealer |
| Ken Michelman | Pick a Number Dealer |
| Clinton Brandhagen | Valet |
| Hayley Mortison | Girl in Hot Tub |
| Gene Ellison-Jones | Mirage Guard at Party |
| Steve 'Biscuit' Walker | Bouncer |
| Rusty Meyers | Club Manager |
| Roxy Swaney | Keno Dealer |
| Billy Morrissette | Paramedic #1 |
| Sharon Mendel | Paramedic #2 |
| Larry Hankin | Preacher |
| Colleen Ann Brah | Wayne Newton Show Fan |
