In "The Pigeon", Ben starts describing the plot of Friday the 13th to his parents, who immediately start questioning themselves over when he could have watched it. So why, in the previous series, did they not question why he was able to describe Pan's Labyrinth in detail?
The Internet, perhaps?
...I'm not asking "How could he have seen this without them knowing?" I'm asking why they reacted to one and not the (much more disturbing) other.
Maybe they all watched it together, having been fooled by the trailer into thinking it was a kid's film?
Firstly, if that was the case, there's no way it would have taken Pete so long to figure out the truth - he would have turned it off after Captain Vidal's scene with the rabbit hunters and Ben wouldn't have seen the Pale Man (in that viewing anyway). Secondly, Ben was trying to pass the scene off as one of his own dreams, not expecting Pete to recognize it from a movie.
Considering that Ben has likely seen most bad films under the sun by this stage, they've likely had this "how did he watch it" conversation by now anyway.
No, this again contradicts the fact that Ben didn't expect his father to recognise it.
Well, Ben has lied about more ridiculous things.
Why didn't they have Pete teach at the same school Jake (and later the other kids) go to?
Because Jake's school is of much better quality and would be unlikely to hire a teacher from the sort of school Pete teaches at. Even if they did have an appropriate opening, which doesn't really happen all that often.