This footprint follows the scene with C at the construction yard---where he stepped in some wet cement. Footprints are critical to the case and they are a recurring theme in The Case of Amontillado.
The bust of Athena follows the scene with C in M's office. The bust is in the background, but her gaze of justice cannot be denied.
The bucket follows another confrontation scene, where C lets M know that he (M) left evidence behind, specifically the bucket...and maybe other items.
One other quality of these pages is that each of the items points to the left --- the sinister side --- like the left-handedness of M. Once C "wins", the images will point right. It's a subliminal thing---I don't expect readers to pick up on it on a conscious level; but putting in these touches is what keeps the work interesting to me.