The Saturday vigil Mass and the Sunday Mass are liturgically the same, and generally have the same readings. Different dioceses have different rules as to when Saturday vigil Mass is celebrated, and it’s usually after 4 PM.
I attended Saturday night Mass for years when I was performing in New York City. St. Malachy’s has an 11 PM Mass, the church is in the theater district, and has been colloquially referred to as “The Actors’ Chapel.” Quite a few Catholics in the entertainment business go to Mass there after performances, and quite a few Catholic theater-goers attend as well. You can tell the performers from the audience people in the pews: The theater-goers are dressed elegantly. Most of the performers are casually dressed and have bits of stage makeup still on their skin. It worked out very well for me schedule-wise: I had to be at company class from my old ballet company at 8 AM on Sunday mornings, whether or not there had been a performance the previous night. Most of the ballets finished at around ten pm. That gave me enough time for curtain calls, getting out of costume and most of the makeup, into street clothes, and a dash from Lincoln Center to the church in time for a few minutes of prayer before Mass. The Catholic performers who went week after week turned themselves into a kind of quasi-parish, since we started to recognize each other there. Matter of fact, a lot of us ended up joining that parish.
Go to their website, and you will see the names of many stars of the past who served Mass there, or were married or buried from there.
It really was pretty cool.