Chris,
On that particular film, yep, I agree with John as usual

. And remember that Oliver was being manipulated and mistreated and Dickens' book is really a pretty dark tale, even in the toned-down film versions we usually see.
You may find that all kinds of things trigger you. That is, they don't have to be scary or threatening in themselves; it's just that they connect somehow with what happened to you and set off in your mind memories and feelings from those bad times.
For example, the man who abused me used a lot of a certain sweet after-shave. There's of course nothing frightening or dangerous about after-shave, right? But for a long time, when I smelled that brand, then in my mind it triggered that connection with the abuser and brought back the bad memories and feelings.
A therapist can usually help you with this kind of thing, Chris. Just remember you're not "losing it" or overreacting. This kind of thing often happens to survivors, and when it does, the best thing to do is exactly what you are doing - talking about it.
Much love,
Larry