There's just so many to pick from.... spoilers ahead for all of the first 6 episodes !! I personally think Ep 6 is my favourite so far

Episode 1-2: 

• The flashback scenes of teen!Eugene in America. I can't seem to find the actor's name anywhere but that scene of him cutting his hair short was really symbolic...
• Dong Mae's introduction... how we're shown right away that he has a more humane/compassionate side to him
• Dong Mae tending to Hina's wound... I still want to see more of what shapes the dynamic between these two
• That first encounter scene with Eugene and Ae Shin... them staring at each other on either side of the train tracks afterwards

Episode 3:

• Ae Shin and Eugene confirming that they know each others' identities/involvement in the shooting
• "What is 'love'?" 
• Dong Mae protecting Ae Shin 
• The boat scene !
• First meeting between Dong Mae and Eugene

Episode 4: 

• That awkward encounter at the hotel
• Dong Mae buying the candies was endearing
• Eugene admitting that he's protecting Ae Shin ("because he can")

Episode 5:

• Ae Shin awkwardly excusing herself from the hotel meeting with Hui Sung and Eugene's awkward response (plus the impromptu walk that ensues afterwards)
• The scene at the hut where Ae Shin points her gun at Eugene

Episode 6: 

• As you said, the bar scene was quite possibly the highlight of the episode (and also the encounter in the hotel where the 3 main guys meet)
• The skirt scene with Dong Mae and Ae Shin... amazing acting from both actors
• All the Eugene and Dong Mae interactions in this ep were gold... that kinda rivalry/bromance with jealous feelings in the mix
• Ae Shin returning the stolen gun (and the scenes afterwards... "the safest place in Joseon is by my side")
• Eugene humiliating Minister Lee in public
• The ending... that cliffhanger?