When Martin is telling Eddie the difference between his pig and banana chew toys, it's easy to see that Eddie is taking cues from his off-screen trainer.
During the ball, the musicians playing in the orchestra clearly are not playing the music. Several of the violinists are conspicuously holding their bows several inches above their violins as they pretend to play.
After Niles says "I adore you" while doing the Tango with Daphne, he goes to cover his mouth, but he instead puts his hand on his chin and barely touches his mouth.