The end of his review of Nightmare City features a parody/reenactment of the ending to Super Mario Bros. 2, complete with the soundtrack.
He did this earlier at the end of his review of Day of the Dead 2.
Sometimes he likes to subvert the expectations his fans have about his shout-outs. One time, he said that the viewer was probably expecting a clip of The Doctor saying "I don't want to go!" (the Tenth Doctor's last words). He instead shows a clip of the Third Doctor saying "I don't want to go."
The entire sketch on the end of his second Funny Games review is a tribute to the Tenth Doctor's departure.