  In [Phys. Lett. B 780, 216 (2018)], Capolupo et al. calculate the noncyclic
geometric phases associated with neutrino flavor transitions in the
two-neutrino scenario, and claim that the results depend on the choice of
representations of neutrino mixing matrix thus can be use to distinguish
between Dirac and Majorana neutrinos. In this paper, we show that their
calculation is flawed due to incorrect application of the definition of
noncyclic geometric phase and the omission of one term in Wolfenstein effective
Hamiltonian. Their results are neither gauge invariant nor lepton field
rephasing invariant. We present an alternative calculation, which is solely in
order to demonstrate that the Majorana CP-violating phase enters the geometric
phase essentially by lepton field rephasing transformation. We point out that
the seemingly nontrivial dependence of geometric phase on Majorana CP-violating
phase presented in [Phys. Lett. B 780, 216 (2018)] is unphysical and thus
unmeasurable.
