When Ryan and Esposito walk up to Beckett's desk to show her the missing poster they found, Ryan is holding it with the image facing out, but after the camera cuts back to them following Beckett's comment, the image is facing away.
When Castle and crew search Damien/Jonas Westphall's apartment they find a broken bottle that is labeled; "India Black Fountain Pen Ink". India Ink is used with dip pens. It dries too quickly to be used in pens with reservoirs, aka fountain pens.