- In her first visit, Tangina tells the Freeling family that Carol Anne sees the beast as "another child". This seems incredibly fishy, since the first time Diane got to talk with her daughter through the TV, Carol Anne said "There's somebody here" and then started screaming bloody murder. Is Carol Anne intensely afraid of other children, is Tangina lying about this for some reason, or is there something else going on?
- The Beast is a thoroughly evil, calculating creature that knows how to best trap / trick you; the unfortunate souls who are his victims (all the other souls in the other dimension) however, are not as manipulative and are not deceiving Carol Anne at all (in fact they are so desparate that they don't care at all that they are scaring the crap out of Carol Anne). So yes, it is logical that the Beast's behavior (disguise, if you will) is different than the rest's.
- The development company built Cuesta Verde on top of a cemetery, moving the headstones but leaving the coffins. And yet they allow the people living there to dig swimming pools? Mr. Freeling even uses how free homeowners are to make modifications to their homes as part of his sales pitch. Is the company not at all afraid that someone's going to dig a little too deep and discover their nasty secret?
- Probably just an oversight in the writing. Also a good excuse to have some scary scenes in the pool with the coffins and bodies. If you really want a good explanation, maybe it was a very old cemetery and the development company also added a bunch of dirt before they did the sodding and landscaping, and figured that between the ground settling and the extra dirt, no one was likely to hit a coffin by putting in a ten foot pool.
- The housing development is located in a narrow valley (as seen when Steven and his boss climb a hill to look down on it). As the troper above pointed out, tons of fill dirt were probably used to level the ground before building (for that matter, they'd need a significant amount of depth just to install a sewage/drainage system for the neighborhood). Also consider that in the hilltop shot, we see that the development is pretty huge, likely much bigger than the original graveyard. Only a relatively small number of lots (including the Freelings') would be located on top of the graveyard. Property owners outside the boundaries of the graveyard proper could dig as deep as they like; they'd probably strike oil before they hit a coffin.
- Or maybe Steven is just wrong about why all those bodies and coffins are popping up out of the ground. We've already seen the ghosts teleporting their grave goods into the Freeling house; they could have used the same process to send the entire contents of their graves back to their original locations. In truth, the bodies might have been dumped in a landfill rather than the construction company having to dig hundreds of holes on the hilltop (and then doing so again when the next phase of development installed more houses on the valley's rim).
- Many people have wondered why only the Freeling family was haunted when many other people also lived on top of the graveyard. The movie has two scenes that explain this: one in which Steven tells a prospective buyer that his was the first family to move into the neighborhood, and another in which Steven's boss mentions that Carol Anne was born in the house. The novelization makes it even more explicit: Carol Anne possessed an extremely powerful life-force since birth, and because she was born in the burial ground, all the ghosts immediately flocked to her. The real question then becomes...why didn't the Freelings start experiencing paranormal activity immediately after Carol Anne was born? Why did the ghosts just hang around chilling for five years until the events of the movie?
- Maybe the ghosts, or more specifically the Reverend, required a conscious mind rather than just a living body. They had to wait until Carol Anne was enough of her own person to manipulate her and get her to do things for them.
- One has to consider that the ghosts haunting the house weren't malicious by any means, the events unfolding in the movie were all the Beast's doing, if it wasn't for that dark entity then the ghosts most likely would have remained enthralled by Caron Anne's spiritual force but without doing anything hostile. As for why the Beast didn't act sooner, my guess is that he had to build up "strength" (in a metaphysical sense, of course) to enact his plans, as Tangina explains that punching through the dimensional barriers in order to manifest in the material world isn't exactly a small feat.
- Don't forget the dead canary scene, and how its little coffin-box got plowed up so the Freelings' pool could be installed. Sure, it's just a bird, but symbolism is bound to be very meaningful to ghosts, given that their state of being is all mental, not physical. Having yet another grave, however tiny, violated in the same way as their own probably gave the otherwise-benign spirits a surge of angry power, which Kane's ghost hijacked and directed towards breaching the barriers. At which point, the really intense hauntings get started, of a kind that the Freeling adults can't just brush off as ground tremors or their daughter sleepwalking.
Headscratchers / Poltergeist