  Bartkiewicz et al. [Phys. Rev. A 91, 012103 (2015)] provided an alternative
analysis of experiment performed by Danan et al. [Phys. Rev. Lett. 111, 240402
(2013)] which presented surprising evidence regarding the past of photons
passing through an interferometer. They argued that the quantity used by Danan
et al. is not a suitable which-path witness, and proposed an alternative. It is
argued that the quantum and classical analyses of Bartkiewicz et al. are
inconsistent and both are inappropriate for describing the past of photons in a
properly working interferometer.
