When Frasier (Kelsey Grammer) is in the video shop trying to rent the movie How Green Was My Valley (1941), behind the clerk on the wall is a list of coming videos. "Coming" is spelled "Comming".
Video store movies are supposed to be listed alphabetically but in the comedy section Austin Powers is shown after Ghostbusters and Home Alone and another copy is featured after Clue.
When he realizes he was in the wrong for spiriting Doug Harvey out of Cafe Nervosa, Frasier pledges on-air to call him in order to make amends. It's not explained, however, how Frasier would know Harvey's phone number or even his name.
When Frasier finds out he's being sued for assault he insists he barely touched the man. Assault is covered under both criminal law and 'tort law' which is handled by civil courts. Under both laws, assault is defined as the threat of physical harm coupled with an apparent, present ability to cause the harm. Battery is the charge when actual physical contact. Additionally, while the man may have been within his rights to sue for assault, under tort law he would've had to prove he suffered harm or loss as a result of Frasier's actions.
Niles makes a reference to Dirty Harry and Emily Post. He has already established his complete ignorance of pop culture by now and would have no idea who Dirty Harry was.