I adore this movie & have watched dozens of times
Ruby is so hysterically crying in the hotel room one minute with face & hair all a mess
almost the next scene, Ruby is all bright eyes & beautifully made-up & dressed at the party
not gonna happen, folks
There is actually some time between Jack leaving the hotel room and him going to the party, where he sits at the bar drinking (more like downing) a few beers. It's just one shot, but that gives her time to freshen up and dress. I think he's been there for a beer or 4, maybe 5, so about 10 minutes?
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Nyuk, nyuk, nyuk spugudy-dunk.
Juicy Plum, Sir?
As a matter of fact, it could easily happen, especially since we are given the impression that she took a good while to get to the party. We know this because we see Jack sitting a bar, presumably for some time, before he goes into the party. It's not spelled out in so many words, but the impression is that Jack went to the bar to get his nerve up about telling Ziggy that Ruby wasn't coming to the shindig. He probably sat there for a good while, 30 to 60 minutes, easy, which would be plenty of time for Ruby to fix her face and hair, get dressed and even arrive at the party well before Jack does. When we next see her, she is surrounded by well-wishers at the party and Jack is stunned to see her there at all, let alone looking like a million bucks! Hope this keeps this scene from driving you nuts in the future.
"Truth -- say it now, or die lyin'"...Fergus (ROAR)