The singer and a ton of extras were on hand Saturday morning in NYC, where director Todd Phillips and co. were shooting a scene for the forthcoming sequel to 2019's 'Joker.' As you may have heard by now, Gaga signed on to portray Harley Quinn ... and here she is.

Indeed ... LG could be seen in her full costume and makeup as the Clown Prince of Gotham's famed love interest, and in these shots -- she's coming down some courthouse steps amid what appears to be a massive (staged) protest ... with "Gotham City" cops everywhere.

From the looks of it ... Gaga's Harley is very much like Joaquin Phoenix's Joker -- namely, quite realistic and not so cartoon-y ... unlike other depictions of the characters in DC films.

Of course, with Gaga's version of HQ now out ... the comparisons between her take and Margot Robbie's iteration are going to start flying in film circles. MR has been playing Harley Quinn for a while now (3 films, actually) ... and her portrayal has been well-received.

Based on what we can glean from these photos (and this vibe), however, something tells us Gaga's Harley might, perhaps, be a little darker ... and maybe even a little less giggly.

Time will tell ... we'll just have to wait and see when the flick comes out in Oct. 2024.

BTW, one last observation ... the very many background actors working today appear to have had their grievances heard when it comes to bathroom breaks. As we reported ... a lot of the extras were pissed they were having to work long hours without getting a chance to whizz.

Peep all the porta potties lining the streets ... as the actors walk by. There's more than enough stalls for everyone to empty their bladders ... and one guy even exercised his right!