Photon+jet events are generated using Pythia 8 and their fraction of quark-jet and gluon-jet events are studied by mapping the photon+jet production to parton densities. Measurements had shown that photon+jet momentum imbalance and azimuthal angle correlations have wide distributions even in the absence of a QCD medium. Sources of widening are investigated via parton level processes in Pythia 8, finding that initial-state radiation is the dominant source. Correlations at RHIC energies are shown to have sharper distributions than those at LHC energies, as the effects of vacuum processes become smaller with lower collision energy. Sensitivity of jet observables to the heavy-ion underlying event (UE) are studied using toy events. Jet observables are compared between jets recombined with E-scheme and winner-take-all (WTA) schemes. The jet pointing angle in WTA scheme is found to be much less sensitive to the heavy-ion UE.