It's a harsh lesson to learn, but in a business, always always cover your ass first. The second you find out about a problem, even if it's small write to your manager to "touch base" so that it's in writing and documented. When I had a project and was stuck with difficult coworkers I made sure to CC my boss on emails so he knew that the ball was not dropped on my end (and so idiot coworker knew it would be on him, which made him cooperate). Never assume common sense will prevail over human stupidity and disorganization. It won't. It never does.
The important thing is to make sure that your ass is covered when shit hits the fan so that when the finger pointing starts, you can show you did everything correctly. At best it makes you look responsible and proactive with your job, which any manager will love, at worst, it keeps the buck from landing on you.
Your manager is likely in trouble as well. A canceled contract also falls on their chopping block. They're going to make sure their own ass is covered.
So... basically. Yes. They can use you as a scape goat. You weren't proactive enough, and while they probably knew what was going on, it's not documented anywhere that can be pointed back at them. They can all claim ignorance if there's nothing in writing, and no phone logs to show they were informed of the situation.
In the mean time, document what did happened and get it written down. Get the numbers, stick to the facts. The fact that a manager left early is irrelevant. They will no doubt be putting a foot up his ass as well. If the numbers are correct, they'll speak for themselves. Say what you did, how you tried to solve it, and how you did in fact contact management. Tell them that even if they were contacted earlier that the numbers still wouldn't have been able to add up.
Then when the meeting is over, write to them to go over what was said, so that is documented as well so there's no he said she said going on afterwards.