Question: It was discovered that Chucky was able to transfer his soul into Andy's Good Guy in the first movie by not only saying a chant but also using a magic amulet. So why, in the other three movies, when he is starting the chant does he not need the amulet to transfer his soul out of the doll into someone else, but in this movie, he needs to use it if he wants to return to his own body?
Question: Why is David known as "the gay friend"? There is no point in the movie where he or anyone else says he's gay.
Answer: When he and the girl are talking in the start of the movie they clearly reference a past boyfriend of his - she says "you loved him right", and the response was "but then his mother found our love letters and that was then end of that."
Answer: There's two possible explanations. First, and the most likely, is that this is simply what's referred to as a "retcon." (Short for "Retroactive Continuity") A term to describe new information/rules/backstory/etc. that are introduced in order to alter the path of a story, or impose new ideas into a narrative. In this case, the series creator and writer Don Mancini needed a reason for the characters to go on a road-trip, hence he created this new idea for an amulet that Chucky need to obtain. And basically, Mancini himself has admitted that he will often change the rules for the series as needed from film to film based on the story he wants to tell, which makes this the more plausible explanation. The second possible explanation is that you could argue that the amulet will allow Chucky to transfer his soul regardless of how long he's been in the doll's body, surpassing the time limit imposed in previous films. But in all seriousness, the former is the more likely explanation. They just needed a new story-element to justify the road-trip aspect of the story.
TedStixon
Both answers work for me. Thank you.