Blitzen's vocalizer does work, but the audio is reversed. If you record Blitzen's voice and reverse it in an audio editing program, you can hear what he is saying. He tries to warn Santa and Bernard about the events that are about to transpire in the movie.
(At around one minute) A small boy sings and writes a letter "To Santa". Clearly visible as the frame zooms in are specific phrases. Notably, the second paragraph showing "All human beings are..." "and endowed by"; showing texts like a modified version of the Declaration of Independence were used instead of an actual letter to Santa.
The pose of the Mrs. Claus statue right inside the "Santa's Pancake Palace" is a nod the "Big Boy" statue usually found at a "Big Boy" restaurant (which, by the way, used to be known as "Bob's Big Boy" until it was bought by Marriott in 1987). In the 1980s and 1990s, the "Big Boy" statue was also a favorite kidnapping target of college students who would usually return the statue unharmed.
Throughout this movie, you will find all of the twelve days of Christmas, these include images of the drummers drumming on the side of the wagon, murals on the wall in the pancake palace, and the music in the elevator.