film acting versus stage acting

Before watching Arsenic and Old Lace for class I had only seen it performed on-stage.  Although I enjoyed the film version, I couldn't help but notice how many theatrical elements had been carried from stage to screen. Cary Grant's character, Mortimer, seemed to exhibit most of these traits through his exaggerated facial expressions, comedic physicality, and the elevated volume at which he spoke. Like most British actors (if not all), Grant began his acting career in theater before transitioning to film, which is a completely different style of acting. In the film version of Arsenic and Old Lace there were times when it seemed like he was performing on-stage instead of on set. I found this a little distracting, especially when it was incongruous with the style of the other actors, who were more understated. I'm not doubting his acting skills. I think he was amazingly talented. But the juxtaposition between Grant's explosive technique and the subtlety of his colleagues' was interesting to say the least, if not a little unusual.