As Walter falls asleep to the tune of Row Row Row Your Boat, he flashes back to his work "cultivating" soldiers. They all appear to be clones, maybe of Christopher Penrose? Notice the Massive Dynamic logo on the incubators.
Here you will find screen captures of each episode of Fringe which are of special interest and/or that contain easter eggs. Easter eggs are hidden content intentionally inserted by the creators of Fringe. If you would like to request a screencap, you can do so by leaving a comment here.