The study of neutrino flavour oscillations in astrophysical sources has been boosted in the last two decades thanks to achievements in experimental neutrino physics and observational astronomy. We here discuss two cases of interest in the modelling of short and long gamma-ray bursts (GRBs): hypercritical, i.e. highly super-Eddington spherical/disk accretion onto a neutron star (NS)/black hole (BH). We show that in both systems the ambient conditions of density and temperature imply the occurrence of neutrino flavour oscillations, with a relevant role of neutrino self-interactions.