Ha good catch. I think it's due to an incorrect raw radar point there. This is the reason why we need this tool: to quickly find these issues. There is actually an AR version of this where we have a human-size 3D point cloud - much easier to debug [1]

[1]: https://photos.app.goo.gl/iTyFKrZtVDiBrNJx7

It seems to be a hidden ninja throwing disc, concealed to avoid airport detection.

Probably just an artifact. There's a 'radar raw' point in there, if you zoom in it is clearly associated with the disk.