We can often learn valuable writing lessons when watching movies. Last night, my husband and I watched The Heat. The movie was entertaining, but there were many times I had to remind myself it was a comedy. Police Brutality should be the McCarthy character's middle name. In the real world, most of her cases couldn't go to trial because she steps way outside the legal limits of the law to make an arrest. She even threatens, intimidates, and verbally abuses her fellow officers and commanding officer. She should have already been fired.
Today's audience, whether it be moviegoers or readers, usually understands the basics of law enforcement. They know an investigator isn't going to get away with beating the bad guy unless it is a case of self-defense or easily explainable in some way in which it his word against the investigator's. In many films, the beating is meant to obtain evidence, no arrest is made, and the bad guy has no desire to report the abuse because of their criminal activity. In these type of movies, the investigator is most likely after someone who killed their partner or a member of their family. These are not usually comedies. More like a Dirty Harry film.
If the investigator is rude and disrespectful to his boss, we need to know why this character is able to get away with this type of behavior. Does the investigator have something on his boss which can cause him to be fired? Do they have history which makes it plausible for them both to speak to each other in an unprofessional manner? Your readers/audience will want to know.
Comedies are meant to be funny, but you need to decide if your comedy is going to work within the limits of reality or if you are going to step over all of the lines. In the Lethal Weapon movies, the comedy works within the confines of reality. The Mel Gibson character may step over the line, but he usually gets in trouble with his boss and in the end everything is tied up in a way the audience can accept. In The Heat, the writers step over the lines in the first scene, which prepares the audience to suspend reality for the rest of the movie. This was a smart move on their part. I only thought "She can't get away with that!" twice before I was able to suspend reality and enjoy the rest of the movie.