Donkey Kong
Right after the line "That's why I'm giving you this hungry stare" (about :50 into the song), you can hear the sound of Mario running and jumping.
Pac-Man
In the middle of the 1st chorus, (about 1:34 into the song) you can hear Pac-Man eating ghosts.
Yes, I played too much Atari in my misspent youth!
![:) :)](./images/smilies/smile.gif)