Rocksteady looks like a freeze frame of the split second before he spit out a mouthful of habanero hot sauce he mistook for a glass of V8 juice.
April...
Yeah, melting was my first impression as well. Either that or she (or someone else??) is wearing a very badly made (lets say bootleg? lol) rubber mask that was somehow supposed to resemble her and failed miserably. Would be funny if there was a Karai the heads could be swapped with.
"Yes, Turtles, I am your friend April! I am here to infiltrate, I mean, uh visit you."