Showtime is the first game to feature Magic Squares rearranged into the center of the backglass.  This game also features the first Magic Line - in this case, a set of four moving numbers that rotate across using an additional two discs behind the backglass.
The ballyhole gives first extra ball, rollovers can extend the time tree to after 5th, triple deck scoring, and corners score as green 5-in-line.
Backglass:

Cabinet:

Playfield:
http://bingo.cdyn.com/machines/bally/show_time/resources/pf-show_time-1.jpg