In a recent paper [Beilstein Journal of Nanotechnology 9, 1405 (2018)], Álvaro Díaz et al. have presented a thorough study of interface electron states in the presence of crossed electric and magnetic fields, the electric field being applied along the growth direction of a band-inverted junction. They have shown that the Dirac cone is robust and persists even if the fields are strong. In addition, they have pointed out that Landau levels of electron states lying in the semiconductor bands can be tailored by the electric field. They have concluded that tunable devices are thus likely to be realizable exploiting the properties studied in this work.