The Easter Egg they Didn't Need.

So on September 26^th Entertainment Weekly ran a quick blurb online about a Batman v Superman Easter Egg almost nobody noticed.  The question got raise, apparently, as to why Superman didn’t use his x-ray vision to see the kryptonite in Batman’s canisters.  Inspection of Batman’s prep work shows the canisters are marked with “Pb”, which is the elemental symbol for “lead”.  Most folks know that Superman can’t see through lead.  A neat little nod to explain the “why”.  Except it actually makes things a little more convoluted than that.

Namely, how would Batman know that Superman can’t see through lead?  On screen we don’t see Superman use his x-ray vision that much.  To my knowledge he doesn’t use it at all in Dawn of Justice, and he used it twice in Man of Steel, once as a kid, once after he turned himself over to the army.  In neither of those instances did it show Superman discovering his lead weakness.  Presumably there aren’t a lot of actual interviews where Superman divulges his weaknesses in this world.  Yes, Christopher Reeve’s Superman spilled the beans to a woman he’d known approximately 1 week, knowing she was going to publish literally everything he said, which shows a tremendous lapse in judgement on his part.  But that’s not the movie we’re talking about here.

No, in this one there is literally nothing in the context of the films we see that indicate that anyone knows he can’t see through lead, or if that weakness even made it into the films at all.  So there is no reason for Batman to use lead canisters to hold kryptonite.

Furthermore, Superman has no idea what kryptonite is.  He doesn’t encounter it until Batman gases him with it early in the fight.  Let’s say the canisters weren’t lead lined and he did look into them.  He would see a glowing green substance and that’s it.  He’d have no idea that this is the one thing that can totally wreck him.

EVEN FURTHER more, in the context of the fight itself it would be MORE beneficial for Batman to not have lead lined canisters, as lead negates kryptonite’s effect on Superman and if it was in, say, a leather pouch, literally anytime Superman got near him he would be physically weakened.

Now it’s entirely likely that Batman had the lead lined canisters not because of Superman’s weakness against lead, but because kryptonite is RADIOACTIVE, meaning that prolonged exposure to it will physically affect Batman himself and he doesn’t want to suffer radiation poisoning while fighting a living titan.

Basically there is a very good reason for Batman to use lead canisters, but it’s not the one everyone is apparently leaping to.