This discussion may contain spoilers!
Having a little trouble getting one of the trophies for the PS3 version...I've tried everything I can think of to get "A Prickly Pair," but nothing seems to work. I have all the other ones, and for those of you having trouble with them, here are the solutions for them...
When the algae guy goes up to the stage to talk about his algae cakes, you can run back to his booth and pick up the box. When you say to Edna you 'Have Something for Her' at her shack in the alternate 1931, before you select Doc you can give these to her. I noticed other people talked about this elsewhere in the forum, but figured I'd put it here just in case.
Before you head down the stairs in the glass house exhibit, open the green door to the left side of the screen, and push the wall you see there. Then close the original green door. When you head downstairs, the walls should move without you having to climb back up and fix anything...at this point, the rest of the maze solution is up to you (though it's not that hard from here on out).
When calling Trixie from the House of the Future exhibit, make sure you use all the dialogue choices available. It should pop after you finish all except your past alias.
Get It On Tape:
This one's tricky. You need to walk up to people at the Expo and 'Use' the bugged Flowerpot on them. The people that need to be done are: Trixie, Artie, the Algae Guy, Jacques, Citizen Brown disguised as Jacques, and Edna. This means you have to locate Emmett BEFORE you record Edna, because her dialogue is story-related and cannot be saved over, and you can only get Jacques and Citizen Brown for a limited time before they are no longer available.
As soon as you get the tickets from Trixie, go to the three open exhibits. You do NOT need to have access to Emmett's for it to work. I am assuming this is no longer possible to get once you have saved Emmett.
Also a little tricky. During the standoff in 1876, knock the barrels off the platform next to the pickle juice. Then, climb up. Put the Tannen sandbag on the chandelier, then put the rest on the pallet. Jump on the pallet and take it down to the ground floor. DO NOT GET OFF. Pick up the sandbag there and put it on the pallet to keep it weighed down. From the ground floor, select the rope, and the barrel will roll into the top of the first column. Push the loose floorboard behind the bar, and the barrel will roll into place above Edna. Climb up for trip #2 and click the sandbag...if you followed these steps, it'll register.
Not hard, but a little time-consuming. At the Expo, keep walking Marty into the Theremin device (the one next to Artie). He'll keep doing different dances in front of it. Keep doing it until he does a moonwalk (you'll know when Tannen's former henchman stares at you). It should pop after the cutscene ends.