Max and Michael are on Liz's roof with the telescope looking to see if Main Street is clear and you can see at the top of the street that there are cars moving on the road when there are supposedly no people in Roswell...
Liz Parker, in a scene where the gang is preparing to cross a street to the UFO centre, is wearing a longer version of the waitress uniform.
When Michael was looking through the telescope, the town was supposed to be dead, but on the top of the telescope there can be seen some traffic movement.
Max, Liz, Isabel, Michael, Maria, Courtney and Tess run to hide in the bathroom of the Crashdown and shut the door behind them. Tess then uses her 'mind warp' power to make the Skins think that the closed bathroom door is a solid wall. Whilst she is doing this, Max and the others are seen looking out of the open doorway to check that the mind warp is working. But they shouldn't be able to see out of the doorway, because the door was shut.