Woah, good catch. I just reproduced the error with the InfoWindow in the OOTB Viewer 3.1.
1. Zoom way out and click on a spot with a lot of close points, therefore activating the pop-up window with little arrows to page through each point feature.
2. Zoom way in and click through the arrows and cycle through the points.
3. Zoom way out (InfoWindow still showing).
4. Pan way over on the map out of the extent of the PopUp window.
5. Pan back over and zoom-in to the pop-up window (same one from original click), and then cycle through and the pop-up window is showing me all of the original field names, with no aliases, and very corrupt looking, and the symbol is overlaid with a black dot as well.