We have studied the effect of gases (NO, CO, Cl-2) on mixed-mode regimes in the Belousov-Zhabotinskyi oscillating chemical reaction in a CSTR. Mixed-mode regimes are characterized by a single large-amplitude oscillation followed by a number of small-amplitude oscillations. Bubbling of the gas into the inflow solution changes the average number of small-amplitude oscillations. We show that the average number of small-amplitude oscillations depends linearly on the gas concentration. A good agreement between the experimental data and simulations with the Gyorgyi-Field model is obtained.