So I'm an Orthodox Jew who actually originally started watching the show because I saw an article about how Jewish it is, and... yeah. Easily the most Jewish piece of popular media I've seen in a while. (Since I'll be covering the whole season, there will be references to spoilers.)

I found a LOT of references to Judaism on the show (which makes sense, as Natasha Lyonne grew up in an Orthodox Jewish family and went to an Orthodox school for part of her education), some of which I think could really have something to do with the many twists and turns the show takes, so I figured I'd just compile them. Some of them I've already written about in comments here. (Note- I'm not really including the stuff like "wow, so much guilt, you must be Jewish" because that's not about Judaism, that's about Jewish people in pop culture. But if anyone noticed those more than I did and wants to mention them, go ahead!)

- Starting off with a small one that people may not have noticed, she said "chag sameach" as an exclamation while talking to Ruth (I think it was laughing-frustrated after discussing some kind of issue, I forget). Chag sameach is Hebrew for Happy Holiday. Not important, but I thought it was funny and a cute Easter egg for Hebrew speakers.

- Max's building having been a yeshiva- I loved this. The idea that the holiness could still reside in a building past used for holy purposes is extremely Jewish. Obviously not "haunting" (Jews don't particularly believe in ghosts), but, say, Jews will often try to preserve old synagogues, even if they're not in use anymore, because they're places where so much prayer and Jewish ritual happened.
I'm actually surprised that all of the reviewers talking about the Tompkins Square Park theory- that the show is about the gentrification of the area- didn't really zero in on the gentrification and loss of the old Jewish Lower East Side, which I think is just as clearly indicated as the park aspect.

- The stuff the rabbi said obviously worked in the context of the plot, but it wasn't particularly Jewish. (And the rabbi looked and sounded like he walked out of a cheap eighties TV show- not Russian Doll's best moment.) I mean, it wasn't NOT Jewish- there's plenty of stuff about the physical vs spiritual world, spiritual wisdom, etc- it was just pretty generic mystic mumbo jumbo.

- Shifra, on the other hand, was great. (The only exception is that no shul rabbi in Manhattan would ever have a problem meeting with an unmarried woman- that bit was obviously only there to a) get John into the scene and b) to have Nadia's interactions specifically be with Shifra rather than with the rabbi.) And the prayer that she says is actually the end of the Nighttime Shema, the prayer said before sleeping. She says "beshem Hashem Elokei Yisrael miyemini Michael umismoli Gavriel milfanai Uriel umei'achorai Refael ve'al roshi shechinat Kel," which she translates as "angels are all around us" but is more accurately translated as "in the name of God the God of Israel, to my right is Michael and to my left is Gabriel, before me is Uriel and behind me is Raphael and above my head is the presence of God." (Michael, Gabriel, Uriel and Raphael are angels.) The idea often comes up on this sub about whether side characters like Horse are "guardian angels" for Nadia and Alan, and the use of this particular prayer I think fits in very well with that.

- The fact that it's Nadia's 36th birthday can have two possible really interesting implications. Basically, one of the most famous numbers in Judaism is 18- the gematria (numerical value) of the letters in the word chai, meaning life. If you ask any Jewishly educated person what the number 36 means, they'll say it's "twice chai." This can have multiple connotations on the show- the intertwining of two lives (Nadia and Alan), the fact that 36 is the age of both Nadia and her mother when they die, the fact that Nadia feels like she is living two lives, her adult life and her childhood that she is still reliving inside of her, etc.
As someone else recently mentioned on a thread, it can have another connotation as well- the 36 hidden tzaddikim, or righteous people in whose merit the world exists and who will live to see the redemption of the Messiah. (The use of the number 36 here is unrelated to double chai.) Anyone could be a hidden tzaddik, and the hidden tzaddikim often will not realize it themselves- and they can be the most unassuming people. To me, my first impression of Horse as a character was that he is in the role that, in a Jewish folk story, would be that of a hidden tzaddik, or possibly Elijah the prophet in disguise. But really, any idea where there are normal-seeming people who could have a hidden depth- one of the most common forms of fan theory on this sub- really brings to mind the idea of the hidden tzaddikim.

- I read an article which made a really interesting comparison of the events of the show to the concept of teshuvah, or achieving forgiveness for sins. Maimonides, in his The Laws of Teshuvah, says that teshuvah requires one to stop doing the sin, come to a reckoning about it, and resolve for the future never to do it again. But for the average person, that's pretty theoretical- life moves on, so one never fully knows that they would not do the same thing again because now there's a whole slew of new situations (which in a sense is the point- the point isn't to dwell, it's to build new instincts to deal with the next situation). However, Maimonides also says that the ideal state of teshuvah is to encounter the same exact scenario and this time do it right. In a sense, the seventh episode is Nadia and Alan doing teshuvah- not necessarily for a sin, but trying to make things right in their minds to achieve self-absolution. They face their fears, realize the root of them, realize that they need to change, and do their best to right the wrongs- culminating in Alan apologizing to Beatrice and Nadia going to see Lucy at the diner. After that, they get a chance to know whether they've done true teshuvah- they get to approach a situation that they'd "messed up" beforehand (when the timelines split in the eighth episode) and redo it. If they can do that, they know they have achieved forgiveness and absolution and truly healed.

If you noticed something I missed, please mention it below!