Crack did not appear until late 1984, while the movie takes place in 1979-1980.
Brick quotes the theme song from Ghostbusters. This film is set approximately five years before that film was released.
MTV did not exist until 1981, and MTV News did not appear until several years after.
It's Cute, How You Think I'm Listening
Neither did guns from the future, to explain this further...
http://tvtropes.org/pmwiki/pmwiki.php/Main/AnachronismStew
Regarding this so-called goof:
"Brick quotes the theme song from Ghostbusters. This film is set approximately five years before that film was released."
This is NOT a goof, since it is well established that Brick Tamland is a time traveler. In the first anchorman, he introduces himself by explaining that in the future it would be discovered that he is "mentally retarded" and then in the second film, when they ask how he got a gun from the future, he just smiles and laughs. The obvious answer is that he got it from the future, DUH!
Brick has visited the future many times.
"Enough of that technical talk, Foo!"