Film Theories and Subtext: ROAD HOUSE (1989) and IMMORTALS (2011)
Once upon a time in one of my writing groups I remember my as-yet-unsold novel Battle for the Wastelands getting criticized for its lack of subtext. At the time I didn't think that criticism was particularly valid, although at this point I don't remember the details and the work has undergone many revisions in the years since then. Overall it is a good idea to imply stuff in the text that's not stated explicitly in order to add depth to your work, get your readers discussing it with each other, etc.
Here are some subtext-driven film theories I've come up with, one very recently and a few years ago. Spoilers ahead, so be ye warned...
Road House-The other night, I saw Road House when my friend Nic was doing a comedy performance with the Atlanta comedy troupe Cineprov. Although nobody in the habit of editing the Wikipeda or TVTropes pages seems to have noticed, I got the implication that Doctor Elizabeth "Doc" Clay (Kelly Lynch) is actually the ex-wife of small-town bully and petty gangster Brad Wesley (Ben Gazzara).
*She references having been married before, but it didn't work out.
*Another character refers to Wesley's wife having left him and him not taking it very well.
*Wesley's new wife or mistress (it's not clear which) looks a lot like Doc. They're both tall and blonde, although the new girl comes off as a lot ditzier and raunchier than, well, a medical doctor.
*Wesley gets REALLY twitchy when he sees Doc over at the room that James Dalton (Patrick Swayze) has rented from a local farmer, especially when she and Dalton start getting busy on the roof outside. He's watching from across the lake for an awkwardly long time and rather than deriving voyeuristic glee out of the situation, he's clearly not a happy camper.
*When Wesley and his crew show up at the Double Deuce club to make trouble, the way he and Doc talk implies they have some sort of history, or at least know each other.
*When Dalton goes to Wesley's house for the final confrontation, Doc arrives just when Dalton is going to finish Wesley after having killed or otherwise incapacitated his goons. That doesn't necessarily mean she's been there before, that she has access to the property, etc. but she would probably be familiar enough with the house and how to get there quickly if she'd lived there before. Someone online theorized that she'd been taken hostage, but Wesley's whole plan was to kill Dalton's friend/mentor Wade Garrett (Sam Elliot) and then have his goon squad waiting in the driveway with guns for Dalton to show up. Not only are all the goons there waiting for Dalton (i.e. nobody is kidnapping Doc separately), but there's no need for Doc to be present at all, since Garrett would have been provocation enough. Also, in their previous conversation, Wesley threatens Dalton, not Doc herself.
Immortals-I saw this a few years ago and although nobody seems to think this besides me, I got the distinct impression that the villainous King Hyperion (Mickey Rourke) is actually the father of the film's hero Theseus (Henry Cavill).
*Theseus is the town outcast, the product of his mother getting raped by a bunch of "peasants."
*When the slimy Lysander (Joseph Morgan) brings this up in front of Hyperion, Hyperion takes offense at his mockery of peasants, claiming that he had been a peasant himself.
*One of the seers has a Bad Future vision of Hyperion and Theseus standing together as allies, which might happen if Theseus learns Hyperion is his father and Hyperion plays his cards right--claims he didn't know Theseus's mother was pregnant, that the gang-rape story isn't actually true, etc. As a young man who grew up without a father, Theseus might be particularly susceptible to Hyperion much like how Luke was tempted by Vader's We Can Rule Together routine in The Empire Strikes Back and Return of the Jedi.
(In the old Expanded Universe novel The Truce at Bakura that takes place immediately after ROTJ Luke momentarily fantasizes about how he could have ruled the Empire--only to realize that even if he had fallen to temptation, him, Vader, and Palpatine would have died with the Death Star.)
Of course, the fact Hyperion killed Theseus's mother in front of him would realistically put a damper on that...
Yes, fan theories are often ridiculous and silly, but I think these have some legs.