I've been in the same position a few times after this and it really is all about reading the room and the people you're talking to.
It was clear the execs I was talking to wanted to get a more "feet on the street" perspective on the project and find out what was really making the project lag behind. I felt like I had nothing to lose and could explain things in a simple manner so they could understand what the issue was and give them a viable alternative that could save the project.
In other situations, I've had the CTO sit in front of a room and berate a dev team I was on for not testing an external app and having it crash a bevy of servers for almost two days while asking if anybody had any answers as to why we didn't test enough. The other situation was getting pulled into a VP's office and ask me why a project wasn't hitting our goals. It felt like more of a "Tell me who I should be firing for this." meeting and I wasn't about to throw anybody under the bus and felt like being honest and speaking up wasn't in my best interest.
I have caught the good and the bad from speaking up but the universal message is to always keep your mouth shut...and that's why we can't have nice things.
I power through and speak up usually, but most people are deathly afraid to because of the spoken/unspoken "keep your mouth shut" cultural message born of hierarchies. Toxic, and probably the reason people flee corporate life ASAP.