Sorry, Wrong Department

The Naval Observatory makes an appearance in Blondie

I have gotten phone calls from people expecting the voice announcer telling them what time it is. My original phone number was apparently listed as such in some old government handout. It’s a little like the reaction when people call and were expecting (or hoping for) voicemail.

Don't Take 'Any Colour You Like' Literally

XKCD optics error

If you were to put a lens, with a focal length 1/4 of the distance between the prisms, right in between the prisms, you’d definitely bring the light back to nearly a point at the first surface of the second prism. However, the angles of each color will not be what they need to be so that they’ll all come out parallel to each other out the second face.

How do I know this? Because I know what it takes to get all the colors to come out parallel (though not on top of each other).