I gree with you - the movie was hilarious (including the scene that you mentioned).
There are a lot of images from that show which are seared in my mind.
The theme song. Badge number 714. The hammer coming down on the whatever it was at the end of the show.
Joe Friday lecturing some unfortunate guy.
Any one ever notice the similarly of Dragnet's Joe Friday and Star Trek's Mr Spock?...
They were both inspired by the same man LAPD Chief Parker
In the 60's it was the day of Chief Parker's LAPD.
Chief Parker was a hard core and fair conservative of integrity that even liberals respected...
Star Trek's create Gene Roddenberry was ex LAPD and while a liberal he was an admirer of Chief Parker....
Star Trek's Mr.Spock, when first written was in fact base on Gene Roddenberry view of Chief Parker... a man of high principals and integrity if somewhat coldly logical to emotionless....
Dragnet's Joe Friday is also a refection of the same Chief Parker personality