Hey, It's That Voice!: The Japanese-dubbed version of the movies is an interesting case: Most of the voice cast worked in many series of the Gundam saga voicing some of the main characters through the years:
For non S Club 7 fans, Hannah Spearitt also in Seed of Chucky before landing the role of Abby in Primeval - which also starred Jason Flemyng.
The Red Stapler: Inverted. Ever hear of "My Buddy" dolls? They looked a lot like Chucky. And the series effectively scrapped the line.
Played straight as well, as you can buy full-sized Chucky dolls.
Throw It In: Brad Dourif ad-libbed Chucky's infamous "fuck you" in the first film's elevator scene.
What Could Have Been: Child's Play creator Don Mancini original conception of Child's Play was completely different. Originally titled Blood Buddy. The dolls would have synthetic blood and Andy would mix his blood with Buddy's fake blood as part of a blood brother ritual. The doll would come alive as a manifestion of the Andy's ID and kill the people Andy had unexpressed anger toward.
A Chucky video game for consoles was planned, but sadly the Kickstarter project only raised $585 of its $925,000 goal.
The death of the teacher and the factory finale in 2 were both intended to be featured in the original.
The opening scene in Child's Play 3 was originally how Child's Play 2 would have ended (And, in fact, a different version of it is used in some TV versions).
It was also how Child's Play was going to end back when the factory was the intended finale
The evidence locker scene in Bride of Chucky was going to be the opening of Child's Play 2.
The electrocution of Tiffany in Bride of Chucky was how the babysitter died in an earlier draft of the first film's script.
The ending of Curse of Chucky with the court case and Chucky being among the evidence and Fioana being declared legally insane was intended for the beginning of Child's Play 2 with Karen Barclay's character
Revenge: The entire reason Curse of Chucky takes place.
Also, a big part of Chucky's motivation in the original Child's Play:
Chucky: You hear this, you son of a bitch?! I'm gonna get you for it! I'm gonna get you, and I'm gonna get Eddie, NO MATTER WHAT!
Talking to Himself: In Seed, Tiff's voice actor, Jennifer Tilly is a separate, and very main character. They lampshade this about every two minutes.