In Sylvie and Bruno, Sylvie is offered one of two lockets by her father the newly elected King of Elfland (after going down a hole in the ground). One is blue, one is red (first called crimson), she chooses the red one, to which her father seems very happy she chose that one, ostensibly allowing the story to continue.
The Matrix has Alice references. But is the Red Pill and Blue Pill also a Carrol reference? Probably not, but i find the similarity interesting.