  Using the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, we
investigate azimuthal correlations in p--Pb collisions at $\sqrt{s_{_{\rm
NN}}}=5.02$ TeV. Comparison with the experimental data shows that UrQMD can not
reproduce the multiplicity dependence of 2- and 4-particle cumulants,
especially the transition from positive to negative values of $c_{2}\{4\}$ in
high multiplicity events, which has been taken as experimental evidence of
collectivity in p--Pb collisions. Meanwhile, UrQMD can not qualitatively
describe the differential elliptic flow, $v_{2}(p_{\rm T})$, of all charged
hadrons at various multiplicity classes. These discrepancies show that the
simulated hadronic p--Pb systems can not generate enough collective flow as
observed in experiment, the associated hadron emissions are largely influenced
by non-flow effects. However, the characteristic $v_{2}(p_{\rm T})$
mass-ordering of pions, kaons and protons is observed in UrQMD, which is the
consequence of hadronic interactions and not necessarily associated with strong
fluid-like expansions.
