The peculiarities of the molecular-beam epitaxy of monocrystalline indium-doped Pb1−xSnxTe films grown on (111) BaF2 substrates were studied as a function of the indium incorporation rate in the growth process. Statistical analysis of the growth regimes and the films' electrophysical properties show that indium incorporation during the growth process affects both the growth rate and film quality. It is shown that indium inhibits film growth, demonstrating the effect of indium as a surfactant on the growth of PST thin films. The smoothest surface and maximum carrier mobility in Pb1−xSnxTe films (up to 105 cm2/V s at T = 30 K) were achieved in a narrow range of ratios (VPST(In)/VIn ≈ 2-3).