This is the third time Gustavo - the tattooed opponent in the fighting pit - gets his jaw smashed in by Vi. She also fought him at the cannery in The Base Violence Necessary for Change (2021), and when he got admitted to Stillwater after the botched smuggling job in Happy Progress Day! (2021). It can be assumed his jaw guard is in response to the damage that made him unable to speak to Caitlyn, which then led Caitlyn to Vi.
Vi's leather jacket features a two headed dog which is likely a reference to the two headed Murk Wolf (which was seen in earlier episodes) that was used by Singed to create Warwick.
At 1:03, you can see Jinx's hand raised, seemingly placing a bet on Vi in the ring.
According to the subtitles, Violet and Powder's mother is named Felicia.
The song that Felicia plays on the jukebox is the same that Powder and Vander listens to in Some Mysteries Are Better Left Unsolved (2021) while he serves her out of the same cup - including the yellow metal straw - that he gives to Felicia when she says she is pregnant. That cup is also the one that that "Chuck" (Thieram) serves Jinx out of in When These Walls Come Tumbling Down (2021).