Other mistake: During the time when they are telling Mike about chemotherapy, you can see the end of his bed. It's way too short for him to be lying down.
Other mistake: When Mike stops time to hit his boss, he starts getting off the desk. There's a bottle of water on the desk, however, the water is moving around from Mike moving on the desk. How can the water move if time is frozen/paused?
Chosen answer: It was not a dream - Adam Sandler just thought it was. Morty left the remote at Michael's house as a way of letting him know that he has been given a second chance.
Remember, Morty was the Angel of Death. He gave Michael the remote (control) of his life once to do things his way and allowed him to get his earthly material desires. He became CEO of the company but sacrificed all the valuable time he could've spent with his family. At the end, the remote appears to him again. This time it's significance is "temptation" he's being given the chance to take control of things again in real life. Not just in his dream. He knows now the repercussions of wanting the.
... back into our physical body. Remember that God is always in control. Don't take the remote away from him to try to do things your way or you won't like what you find at the end of the Rainbow (Death and regret). What Morty was telling Michael in one scene about the lucky charms metaphor.
I believe it was a dream because he comes home and everything is back to normal the kids are still young his dad is living the dog Sundance is still living and his wife isn't with bill the guy that teaches Ben how to swim. He was living in a different kind of reality.
Sorry I typed to fast I meant it was a dream.