Brentford kept their unbeaten start to the season intact despite playing nearly half-an-hour with 10 men.
Defender Tony Craig was shown a straight red card for a professional foul on David Amoo.
Bees substitute Toumani Diagouraga did find the back of the net, but his close-range effort was ruled out for a foul on goalkeeper Mark Gillespie.
Carlisle's Lee Miller forced David Button into a reflex save after the break with a deflected effort.
The hosts continued to create the better chances, with Adam Forshaw's dipping drive parried by Gillespie and Donaldson's snapshot from the edge of the box blocked.
Brentford then had a late penalty appeal waved away when Clayton Donaldson appeared to have been hauled down in the box.
VIEW FROM THE DRESSING ROOM
Brentford manager Uwe Rosler speaks to BBC London 94.9:
"Carlisle did everything that we expected. They came out with the same formation, the same players. But obviously we didn't expect that they'd put in a centre half in the last minute, we had prepared the whole week for a certain way of play.
"I think we gave the first 45 minutes away, we looked nervous. Not only one player, we looked generally nervous. We lacked mobility, we lacked energy, we lacked movement off the ball, we lacked opportunities for the men on the ball to play.
"In the second half we looked the better team, you could see how fit my players are, how much they were running around and how much quicker they passed the ball. It was all about the tempo of the play, and one or two players gave more life.
"But overall I think that from the 14 players who participated today, we had five players who performed, and that's not enough to win a game in our league."