In Act II the first major issue with communication is between Hal and Falstaff.  Hal knows that Falstaff has a problem eith "stretching the truth" in a big way.  So, instead of going and talking to Falstaff about how he has a problem with lying, and how this problem is effecting his friends, Hal just just decides to set up Falstaff.  So, Falstaff finds out about this problem through being embarrassed.  His friends go behind his back to teach him a lesson