The latest episode, titled 'A561984', managed just 7.29m for ABC - a new low for the series. The previous low was for the last instalment, which aired Thursday, November 19 and drew 8.01m.
FlashForward was beaten in the 8pm hour by Fox's Bones, which had 9.93m, and Survivor: Samoa, which logged 12.75m.
The CW's Vampire Diaries rerun managed 2m, and Community and Parks And Recreation took 5.38m and 4.83m for NBC at 8pm and 8.30pm respectively.
A CSI repeat won the 9pm hour, pulling in 9.88m for CBS. Its nearest rival, ABC's Private Practice, brought in 9.27m.
Fringe had 6.86m for Fox, 1.91m watched The CW's Supernatural rerun, and NBC's The Office and 30 Rock put in 8.06m and 6.17m.
At 10pm, a second episode of Private Practice logged 9.75m for ABC, 10.72m tuned in for a reairing of The Mentalist on CBS, and The Jay Leno Show had 4.73m for NBC.