The scene where Yeoman Kelly Chambers is reduced into genetic goo for use in the construction of Human-Reaper. I seriously wish it showed more of the actual gooificiation, perhaps even Kelly in goo form draining into a pump or something. Oh well, this will have to make due =P
You can unlock this scene if you do any side missions after the abduction of your crew. If you didn’t delay your final mission, Lilith will be in Kelly’s place and Kelly will be saved from gooification.
For those of you who don’t know who Kelly Chambers is, Kelly is Sheperd’s assistant/yeoman, the Normandy’s ( unofficial ) counselor, and a potential romance interest. In my case, she was ( emphasis on “was“ ) Sheperd’s girlfriend.