So Eridan gets... like, to the doors that lead into the place with the elevators and stuff, or whatever, before he realizes something is off.

He's gotten used to the bahanamal stalking him in the Tommy Bahama, which is how he recognizes the same thing is happening now. He's being tailed. And judging from the missing horns... he can bet who by.

The second he opens the doors to go in, he bolts forward, then hangs a sharp right towards the arcade.