Mattel's DKR Batman is based on a Masters of the Universe Classics body, and unintentionally retains the MOTUC' "head swapping" feature. Icarius comes with a second head that's STBLDF Val Kilmer. Val Kilmer starred in Batman Forever. So a Val Kilmer head on a Batman body makes perfect sense - it's not like Mattel is ever going to make a Movie Master figure for him.
Talking of, that's Movie Masters Superman he's next to. Since MotU Classics are perpetually too big and Movie Masters are perpetually too small,* Supes had to be closer to the camera than Batman did in order to look like they were part of the same universe.
Batman's line is a quote from Batman Forever. We knew we'd have to point that out, because nobody remembers anything that was said in Batman Forever. But we bet it's Superman's comment that really needs explanation.
Sean Young was cast as Vicki Vale in Tim Burton's Batman, but broke her arm and had to be replaced with Kim Basinger. So when the sequel rolled around, she felt she was owed a role to make up for the one she missed, and began campaining for Catwoman. Which consisted of dressing up in her own Catwoman costume and wandering around the studio while Tim Burton hid in the bathroom.
So that's what Henry Cavill is referring to.
*Really, Movie Masters are a fairly accurate scale. It's just that the other DC figures they're going to be compared to are slightly oversized.