When the group finishes their ride on the Wonkamobile, Mr. Wonka is handing out suits to protect each person before they enter the Wonkavision room. But there are four people in the group not including Mr. Wonka, and you'll notice that only 3 suits are ever hanging on the pegs. Poor Mrs. Teevee gets overlooked. But in the next scene after they've entered the room, everyone is wearing their protective gear.