Fair enough. Police will disclose and journalists will often report the number of weapons and ammo or any explosive devices found at the perpetrator’s home, even if they were not brought to the scene or used in the crime. I think the ladder is a detail in the same vein because it is equipment that he had available to him.
The mirror DOESN’T flip left and right. Imagine an x-axis as a horizontal line across the mirror, a y-axis as a vertical line up/down the mirror, and a z-axis as a line that comes straight out of/into the mirror.
The mirror is actually only flipping that z-axis that comes out of/into the mirror, by reflecting the light back