Revealing mistake: When the demon breaks into the jail and the cop is standing behind him. When the camera turns back on to the demon, if you look close you can see the zipper in the left hand side of the demon's suit. (01:08:45)
Revealing mistake: In the closeup of the demon monster you can see the contact in his eye.
Revealing mistake: During the final showdown, where the Creeper is holding Darry hostage, as the camera zooms in towards the Creeper's face when it is screaming intensely, you can see the nose and teeth of the actor underneath the make-up/suit.
Answer: There's no reason he couldn't use a gas station. In the dark he just looks like a guy with dark skin, unkempt hair, and a trench coat. Even if somebody does get close enough to get a good look at him, he would easily kill them to keep his secret.
BaconIsMyBFF