Plot hole: After Rita kills Billy, why didn't any of the other rangers do something to help him? They could have very easily done CPR on him or at least called for an ambulance.
Continuity mistake: When Kimberly's friends are breaking up with her the arms of the girl with the pink and gray blouse change position between shots. Also in one shot she is touching her face in the next she has a cell phone in her hands.
Continuity mistake: When the red haired bully is disturbing Billy in the detention classroom his right sleeve changes from up to down between shots.
Continuity mistake: When the bully hits Billy and throws the blue folder to the floor, it reappears in his hands in few shots later.
Continuity mistake: When Billy helps Jason with the tracking device he hugs him and palms with the right hand, then with the left.
Continuity mistake: When Jason slaps the bully in detention the distance between them changes from shot to shot.
Answer: Rita was a part of Zordon's original team, but she betrayed them in her search for the Zeo crystals. She even killed the original members of Zordon's team until only Zordon's remained.