Doug was not a man of this country. Heck, he wasn't even a person from this planet at all. He knew that if the authority found out that he was a Skrull they would lock him up and torture him for attempting an attack on Earth. Doug would never do something like that to this planet but the law wouldn't listen anyway.
Since the news of the Registration Act has been reached to Doug, he finds himself underground in an attempt to not be discovered. He began his search for anyone else who was oppose to this law, hoping that he was not alone in this desperate hour.
Doug saw a ladder, leading up to the surface. He reached out his hands onto the cold, slimy metal bars on the ladder and began to climb. Once he got to the very top, Doug turned his fists into orange-colored rock fists, similar to the Thing's; and pushed the manhole above him. Once it was lifted, Doug slowly placed the manhole down on the ground to make sure he didn't make a loud noise. He slowly poked his head out of the hole to see that he was in an alley with no one around. He could hear people in the streets, walking down the sidewalk just by the exit of the alley. Doug shapeshifted himself into his human form as he crawled out of the sewers. He dusted himself off and walked into the streets, to blend in with the people walking by.
Doug knew no one saw him shapeshift but if they did, they would never think of attacking or engaging him in a public area like the one he is in right now.