Manager Harry Redknapp admitted in his programme notes that progressing from the fourth round was not high on his list of priorities, but he will have been shocked by his side's inept display.
With Tuesday's clash against Manchester City in mind, the Premier League's bottom club made nine changes and went behind after four minutes through Armand Traore's own goal.
Shaun Williams' fourth-minute corner to the near post was put into his own goal by Traore under pressure from Dean Lewington.
QPR dominated the first half but paid for wasteful finishing when Ryan Lowe raced clear to extend the npower League One side's lead five minutes before the break.
A long ball from Antony Kay caught QPR, namely Anton Ferdinand, napping and Lowe slotted past Rob Green.
Karl Robinson's side did not stop there, though, making a mockery of their position 31 places lower than QPR in the standings to progress to the last 16 in style.
Substitute Ryan Harley netted from close range five minutes after the restart and Darren Potter extended the Dons' lead even further with a superb curling effort to the disbelief of the 3,155 visiting fans.
Jay Bothroyd nodded home in the 83rd minute after Bobby Zamora's tee-up, and Fabio scored in stoppage time from a Bothroyd touch, but it proved just a consolation on a terrible day in the Hoops' recent history.