Manager Harry Redknapp handed former Manchester United centre-back Ferdinand a start before he made way after 45 minutes, with Caulker coming on at the interval in a host of changes.
Jack Collison, who is on trial with the Loftus Road side as he looks to earn a permanent contract, was also introduced for the second period.
Leipzig ran out 2-0 winners with both goals coming in the second half as Yussuf Poulsen struck in the 62nd and 73rd minutes.
The opening goal came when Poulsen escaped the attentions of Richard Dunne before firing home from inside the box.
And he added his second 11 minutes later after being set up by Patrick Strauss as the Rs continued their preparations for a return to Premier League action.
The match was hit with a deluge just before the interval, with midfielder Joey Barton admitting he was happy all the players involved came through unscathed.
He wrote on Twitter: "Good 45 minutes workout in horrendous conditions. Blazing sun, gale force wind and monsoon all in one half. Madness.
"All the lads got some game time under their belts and came through unscathed. Back home tonight. Few days then off on tour again."