When Wolverine was freed the color should have switched to black and white so he could go full Kill Bill Vol. 1 on the guards.
Or they could have actually had him wear a comic accurate visor and when the doors open the camera switches to his POV but it's all red and cybernetic looking like when you see things from the Terminator's point of view. New viewers might even think the kids really did unleash some sort of robot or freak genetic monster. Then he could have gone on a rampage where you're seeing everything through his eyes, the visor makes everything look red so the blood splashing around wouldn't stand out and they probably could have gotten away with more. When he's done have the camera pan over to Jean as he looks at her, she reaches up and removes the helmet and THEN reveal that it was Hugh Jackman all along. So maybe cool ways they could have done his rampage.