While in the televised version Michael Webster experience being 12, 6 (on his sixth birthday), and a baby in the past, the book has him experience a much longer time reversal, first going into 12, 3rd grade, 2nd grade, kindergarten, nursery school and being a baby.
Michael does not experience getting beaten up by Kevin Flowers or being seen in his underwear.
Michael's dream is different. It is not of a scary version of his birthday. Instead, it is the clock with Tara's head for a cuckoo chasing him.
The first time when Michael's father tells Tara not to touch the clock, the father is also visibly more upset than in the book.
His father is a lot angrier at finding him at Anthony's Antiques than in the book. Later on, when he was brought back to the present it is the actual present, and he gets the same scolding from his father that Tara got earlier. Michael being happy to see his parents again catches his father off guard.
Tara's bedroom is his father's office and not Michael's old bedroom.
Mr. Webster discovers the year 1988 is missing first.
Michael does not mention having his arm broken when he was young in the episode.
This episode was adapted into Goosebumps Presents book #2.
This, "The Haunted Mask", and "Werewolf Skin" are the only TV episodes to not be released on DVD. Though the episode is accessible through iTunes and Netflix.
The second time Michael goes through his birthday, his mother asks him to help her with his cake. When he goes to her, you see they are outside. But the first time of Michael's birthday, they were inside.
In the scene where Michael is dreaming, he opens the door to the room the cuckoo clock is in and begins to scream. But we hear the scream a split second, before his mouth opens.
The first time when Michael's father tells Tara not to touch the clock, you see she has bangs on her forehead. But when she turns around to stick her tongue out at Michael, her bangs are gone.
This episode, along with "The Girl Who Cried Monster", on their original premieres had a special opening theme in which there was a ten-second remix when R.L. Stine is walking through the grass with the briefcase. When the G passes the dog, that part of the music is played with a different instrument. There were also different scenes from the television show when the door opened.
When Michael looks in the mirror at age 6, his scream and facial expression is exactly the same as Macaulay Culkin's scream in the Home Alone movies (and he also bears a resemblance to him).