Hey! I remember watching this show on PHL 17 as part of PTEN (followed by KUNG FU: THE LEGEND CONTINUES). This show was truly awesome and I hope that Warner Home Video releases it on DVD!
The phaser gun is a car alarm casing, when you press one button it will shoot to paralyze someone for certain amount of minuets just enough to numb them to put handcuffs on and put them in a police craft. Then other button is to send that person back into the future.
Actually, the name SELMA is an acronym of SELective Memory Archive. SELMA was Darian Lambert's source for various 20th century information... as well as his ATM card! ;-)