I found the Jason Voorghees' cameo in the jungle too bad you can't repair the chainsaw you get there.
I also found a really nasty bug: under certain circunstances apparently involving the amount and kind of stuff I have in my inventory (it seems to happen when it's full, but doesn't happen every time it's full) when I use a mod to build something, some of the stuff I have in my quick inventory (R2) disappears (it doesn't show in the full inventory list, nor is it dropped to the floor). First time I losed a quite decent golden pistol when checking what the piranha mod was about, second time I losed three swords when making pistol and rifle ammunition (fortunately this second time I rebooted the console before it saved, so I finally didn't really lose anything).
I think it might have something to do with the way the game handles building items (if you make a new weapon and you already have 8 weapons in the weapon slots, the new one is automatically assigned to your current quick inventory slot and you get two status messages as if you had picked up both the new weapon and the weapon that was replaced from the quick inventory), combined with the weird way it seems to handle some of the items. Eg. 20 first aid kits only take one inventory slot, yet sometimes if my inventory is full I can't pick up a new one even if I have only about 12 of them
And then there's the fact that weapons built with mods that don't require base weapons (eg. developer mods) disappear if your inventory is full... all that probably sums up as several potential WTF situations.
I have only found that bug twice in the... hmmm... about 60 hours I've spent with this game
but it happens.
Anyway, I'm at 96% of my second playthrough
I thought I had picked up all the secondary missions on the first one, but turns out I missed quite a few.