I'd heard about the Point of No Return so before I rescued Lili, I decided to try and bump up my rank level by going back and finding more figments, PSI cards, etc, and also finishing the Scavenger Hunt.
My warning to other gamers is once you return a single brain to Ford back in his lab, you can no longer get an upgrade from him. Period. He stands overlooking the Lab and that's where he stays. Your choices of conversation are limited to either going back in the field, "What is all this machinery for?" and "Never Mind".
So I completed the Scavenger Hunt but can't get the rank-up for it from Ford.

I know there's a rank-up place after the Point of No Return so I will eventually get the rank-up I should for completing the Scavenger Hunt but I would have preferred gaining all the rank-up's I could before passing that Point of No Return.
My advice is not to return any brains to Ford until you're fully ranked up.

I don't know if you will get credit for the scavenger hunt after the point of no return, but you're not going to the right Ford. You need to go the Ranger Cruller by the Geodesic Psychoisolation Chamber.

Thank you. I accidently discovered the same thing on my 2nd time through the game. I felt like an idiot, to say the least. I was trying to get a Scavenger Hunt upgrade from the wrong Ford Cruller!
One thing everyone should know, though, is that you do NOT get an upgrade for your completed Scavnger Hunt when you pass the Point of No Return. I went up to the Fortune Teller's booth at the beginning of the end level and the dude didn't give me anything for the completed Scavenger Hunt.
I was still able to complete the game but I didn't get up to rank 100 or even 95. I think I ended up at 94 (I kept missing figments, especially the ones that drift by, like in the Basic Braining rotating log path).

No problem - I had one hell of a time finding the right Cruller too.
I probably used up 30+ astral projection layers trying to get all the figments from the Basic Braining - it's a pain, but hopefully worth it.