Gaffes

Throughout out the series, it's clear that the actors/actresses portraying teenagers are actually in their 20s+. This is done as to not interfere with the schooling of real teenagers and to give the general viewing audience who are teenagers themselves someone they can look up to.

There is a high priced military school, New Mexico Military Institute, on the north side of Roswell. During the weekends, cadets from this school flood local restaurants to eat something other than institutional food. Many staff members from the school also wear uniforms. Despite all the scenes in the Crashdown Cafe, it is rare to see anyone in uniform in the cafe.

Max and Isabel's Jeep is an automatic (they often drive away with both hands on the steering wheel), but the audio makes the Jeep sound like a standard stick.

In a number of episodes, there are transition/establishing shots with saguaro cacti in the desert. Saguaros are not found in any desert in New Mexico.

For taking place in arid southern New Mexico (and some episodes in equally arid southern Arizona), there is a surprisingly amount of rain - as evidenced in the copious shots with wet streets.