It's probably just a case of Egg, who isn't a particularly bright man, seizing upon an opportunity to jokingly reference a famous film he hasn't seen. "Sophie's choice! That's a thing, isn't it?!"
The production team presumably haven't seen it either; they kept it in because it sounds like a bit of classic Egg banter. He said something meaningless and laughed, so that'll do.
But if he cracks wise about Schindler's List in the next episode, then we could be on to something.
EDIT: What Shoulders said.