Alex Hales was the only shining light in a drab Notts batting effort as Lancashire chased down a 10 over Duckworth-Lewis target with apparent ease.
Hales scored 83 but only Chris Read (11) joined him in double figures as McCullum, Smith and Keedy prevailed with the ball.
Notts must secure at least one point from their final two Friends Provident t20 matches at Trent Bridge to secure a home quarter-final after the Lancashire spin attack restricted the Outlaws to 138-7 from 20 overs.
“Lancashire’s spinners had a big impact but the ball was wet by the time we were bowling and we couldn’t match their accuracy,” said Notts Director of Cricket Mick Newell.
“It’s disappointing to have lost but our home form has been excellent and we’ll look to get the points we need from the games against Leicestershire and Yorkshire.”
Stephen Moore’s unbeaten 51 helped Lancashire cruise to victory with ten balls to spare in their ten allocated overs.
Floodlit cricket at Trent Bridge:
Notts Outlaws v Leicestershire Foxes (Thursday 15th July, 7pm, Trent Bridge)
The final group fixture:
Notts Outlaws v Yorkshire Carnegie (Saturday 17th July, 6.10pm, Trent Bridge)
Ticket prices:
Adults £15 (£12 in advance)
Senior Citizens £15 (£7 in advance)
Under 16s £8
Click here to buy online
Ticket hotline 0844 811 8711
Tickets also available from the Trent Bridge ticket office