Continuity mistake: Whenever young Riley is pulling the wagon around the house, Fear stops her at a white cord in an outlet. In the next shot, it is a black cord.
Inside Out (2015)
Ending / spoiler
Directed by: Pete Docter, Ronaldo Del Carmen
Starring: Diane Lane, Kyle MacLachlan, Amy Poehler, Rashida Jones
Joy and Sadness return to headquarters and stop Riley from going away. The emotions let sadness make Riley miss her family so she goes home. Then Riley turns 12 and they have a new console installed. There are also bigger and better core memory islands.
More mistakes in Inside Out
Dad's Anger: Uh-oh, she's looking at us. [Turns off TV] What did she say?
Dad's Fear: Uh, sorry, sir, no one was listening.
Dad's Anger: Is it garbage night? Uh, we left the toilet seat up! What? What is it, woman, what?!
Question: How come Sadness was the only one who could change the emotion of the memory orb? Don't we sometimes look back at things we thought we were scared of or sad about, and laugh at them? How come the other emotions can't change them the way Sadness can?
Answer: Sadness can change the memories because of Riley's current situation: she has left the home she loved to move to a new city. This makes her happy memories more susceptible to being changed to sad memories. As she remembers things that used to make her happy they now make her sad because she hasn't accepted her new house as home yet. Presumably under the right circumstances the other emotions could do the same thing, just not all the time.