That’s called an intrusive r: https://en.m.wikipedia.org/wiki/Linking_and_intrusive_R

Originally comes from a final r being pronounced before a word starting with a vowel, and then that cropping up in places with no final r.

French pronunciation has something like this. They can't abide a word that ends in a vowel-sound smooshing into a following word that starts with a vowel-sound. So, for example, the word "suis" is pronounced "swee", unless the next word lacks an initial consonant, in which case the trailing 's' is sounded.

So "Je suis anglais" is pronounced as "Je sweez anglais". Compare "Je suis francais" ("Je swee francais").

Pretty sure that English non-rhoticity started with higher-caste London people trying to sound French.

Interestingly, when people speak slowly it comes out as "je swee zanglais". The terminal sound is deposited onto the following word!

Another example: there's a French children's song with the line: "Pendouillez moi avec" ("hang me as well" - don't ask). I have a recording of this song, and it's pronounced "Pendouillez moi za vec" (equal stress on each of the last three syllables). What's interesting is that the intruding consonant isn't an otherwise-silent 's' that is being sounded; it's completely spurious.

These are called liaison and enchaînement, respectively. Your useless fact for the day.

In most cases, it is more a preservation of sounds that have been dropped elsewhere. But see https://en.wikipedia.org/wiki/Liaison_(French)#Liaison_on_in... , e.g. "parle-t-on", "a-t-il"

This is called “faire la liaison” (“make the link”) between the two words. If the first word ends with a consonant, and the next word starts with a vowel, then do pronounce that last consonant.

As in the Beatles song A Day in the Life:

I saw-r-a film today, oh boooy

Or Oasis’s “Champagne Supernova” sounding (to my American ear) like “supin’ over”.

Also, The Lincoln Lawyer has an Australian actor playing a character (Cisco) with a gruff, throaty American accident, but at one point it slips through and he says “Lisa” as “Liser”.

Yeah, that sounds like classic Scouse to me, but you certainly hear it in other UK regional accents.

Is it a regional thing? I have a very "standard" middle-class home counties English accent and I use the intrusive r.

I'm extremely underqualified (non-native speaker) but first time I heard this and paid attention was from Dave Chinner (linux developer) who is australian and he was using a very pronounced linking r.

I've taken Andrew Ng's coursera courses. I'm almost blind to American dialects (compared to Norwegian dialects the changes feel extremely subtle), but I noticed that one! "Dater science" was definitely on the "agender"! But I don't feel like all Americans have it that strongly.

Common in the States too. I'm from Eastern MA and work in Boston. If I order a "vodka, soda" it sounds normal, but if I say "vodka AND soda" then "vodka" becomes "vodkar". My accent is a pretty standard Eastern New England accent.

Only if the next word starts with a vowel.

Our Aussie data scientist does it at the front of data as well, so if comes out 'dartah'