I am from New England (northeastern US) and it's my understanding that we have a non-rhotic dialect in this region, which is unusual compared to the rest of the US.
It is common to drop the final r in a word, and that is the most singular feature of the dialect, as Tom Bosley's character in Murder, She Wrote famously abused. Car turns into cah; Bar Harbor becomes Bah Hahbah.
One other feature of my native dialect is the intrusive r. This shows up in mysterious places, the examples that spring to mind are idea(r) and area(r), seemingly after terminal "a" sounds.
Similarly, it pops up where one would use non-r word endings like saw, especially when followed by a vowel (perhaps to make it easier to glide from one vowel to another without a glottal stop):
I sore [saw] a black Chevy van parked in front of my house this morning.
Does the intrusive r appear in all non-rhotic dialects? Does it appear only in non-rhotic dialects?
I have been wondering if it is a kind of over-correction, where I hear it at the ends of these words because I am used to hearing a dropped r when a word ends with an a sound. For example, since I hear "cah" as car, I also hear "idea" as idear.