John Shannon and Sarah Williams are apparently keeping things cordial despite their messy split ... because the estranged couple was spotted hanging out together on the same day they filmed their explosive reunion!

TMZ has obtained photos of the "Love Is Blind" stars hanging out at a bar in Burbank, CA on October 24th ... alongside fellow Season 11 stars Erika Ellis and Blake Carver.

Witnesses tell TMZ ... while John and Sarah weren't showing any PDA, Erika and Blake were a different story, getting plenty touchy-feely during the night out.

The sighting is especially surprising considering John admitted during the reunion that he cheated on Sarah with a stripper who also worked as an escort.

As we reported ... John confessed to exchanging inappropriate text messages with the woman after meeting her during a boys' night out, though he insisted nothing physical happened. Sarah said the betrayal ultimately pushed her to walk away from their marriage.

TMZ broke the story ... Sarah filed for divorce in June, just over a year after the pair tied the knot, making them the only couple from Season 11 to actually get married.

Their marriage may be over ... but apparently, last call is still on the table!