Yes, Laughing Bull specifically says something along the lines of "his star is about to fall" to Jet. At the very end of the credits, a unique blue star becomes bright for a moment, then fades away completely.
The lyrics to the final episode's credits, "Blue", are about passing into the after life. For example, the last lines are:
Everything is clearer now
Life is just a dream, you know?
It's never ending
I'm ascending
Spike's last word, "bang", is a reference to the fifth episode, with the boy who was hundreds of years old and couldn't die. He was relieved when he finally could die, and he asked Spike, "do you understand?" Spike saying "bang" just as he died showed that he finally did understand.
"I got kicked off the high school debate team for saying 'Yeah? Well, **** you!'
... I thought I had won."