Copyright is the "right to copy" and typically songs are covered under one of two copyright categories. There is SR copyright (sound recording), and PA copyright, which is performance art. The lyrics, melody, and arrangement are protected, technically. The arrangement refers to sheet music and literally means the score on paper.
Trademark or trade-name status is a different form of protection and is not covered by copyright unless is refers to the artwork that accompanies the trademark. However, you cannot claim copyright on "ideas", lead licks, a guitar solo, bass-line, drum solo. You can copyright music and lyrics (a song), an arrangement (printed sheet music), and the cover art (under VA copyright - Visual Art).
If you mention a product or cartoon character in a song, most likely you will have no issues whatsoever unless the reference is done in an offensive way.
If you are in doubt, consult with an entertainment lawyer.