When Dr. Stone's assistant helps him up from the floor, there's a lopsided, circular diagram drawn on the chalkboard behind them. One shot later, the diagram has changed into a perfectly round circle and has moved itself several inches higher on the board.
This is the only Outer Limits episode that lacks both opening and closing narration. It was absent because "Forms" was the unsold pilot for a series called The Unknown. A second version, stripped of all its supernatural elements (Tone was simply a mad scientist, not a real time traveler), also failed to sell.