Nick is on the phone with the Butterfield Academy. Warrick and Catherine are walking in the opposite direction. The first time we see that scene, the camera following Warrick and Catherine, Nick does not cross their path. Catherine turns her head towards him, to her left. The second time we see that scene, the camera following Nick, he crosses their path and Catherine turns her head towards him, to her right.
During Catherine and Warrick's case, when Nick is on the phone to Butterfield Academy, he walks behind Catherine and Warrick. However, during this section of his case, that same scene from Nick's point of view shows him walking in front of Catherine and Warrick.