I think Jerry wandered into the Lodge, or maybe the Lodge spirits are screwing with him, having a laugh at his expense.

Because, really, I've never had weed that made me attack my own foot in the belief it wasn't my foot. And if his experience isn't Lodge-induced, he's into a lot more than Mary Jane.

Although perhaps it was just a highly elaborate "my foot" gag, as in, "Alternate dimensions, my foot." And the scene, if I remember right, comes after Tammy questions Hastings and Gordon makes the most awkward request for a cigarette ever committed to film.

I thought it was great! 

Maybe a visit to Dr Jacoby is in order?

For me, I feel that Jerry is undergoing a psychotic episode. It doesn't feel like the other supernatural elements where people's limbs have a literal life of their own. It seems that when Jerry calls Ben from the woods, that he's scared, and lost and unable to find his bearings. He doesn't know why he's in the woods, he's lost his car. The idea that someone stole it feels paranoid. I think he's suffering from an actual psychological disorder, some type of dementia. It doesn't seem to be presented to us in the same way as, say, Bill Hasting's experience, which, bizarre as it is, he at least is sure of having happened in the way he has experienced it. He's sure that he's experienced that nightmare in that way for real. Jerry is totally unsure of what's happening. I think that Jerry's experiencing a form of xenomelia, a psychotic dissociation of the limbs. Although his experience has a lot in common with the experience of others in the show, I think in his case it's all in his mind. 

I really doubt it, or at least, I very much doubt that's the whole story.  Maybe Jerry is losing his marbles but I am certain it will lead to something else.  I have a feeling in me bones that there won't be any dead ends in this series.  Maybe a few things will be open ended enough to justify a fourth series but something that the story keeps coming back to is, IMO, far too important than a simple matter of watching Jerry turn into a drooling, incontinent husk.

There is a history of mental illness in the family. Not just Johnny, but Ben too. Remember in Season 2 when Ben thought he was in the civil war?

It's possible that Jerry's cannabis use has tipped him over into mental illness.

Right. I think this is a weed related breakdown. It's set up in a different way to the other experiences. Jerry is confused and mystified in a way that the others aren't. The others are defending themselves against apparitions they can see. They know what they're up against. Until the talking foot we saw Jerry afraid, but not with any reason. It was just him and his fear, as though it was coming from within. 

I think that what they may be doing is saying something like, 'people have out of body experiences that are linked to mental illness. And for Dale, for Bill, and the others, that is not what's happening. Jerry's psychotic experience and the others' may superficially have things in common, but they're utterly different.' Time will tell.

Personally, I'm waiting for Jerry to encounter a human-sized walking owl on his trek in the woods, you know, like the human-sized walking owls mentioned in Frost's book.