Barton meets with Maya at midnight, and the fight and discussion could not last more than an hour, after which Barton and Kate are picked up by a ride-sharing service car. The car drops them off in Manhattan in the early morning but at least an hour after dawn. In late December, dawn in Manhattan is about a quarter after 7, which would place them getting out of the car no earlier than 8am. Even with Manhattan traffic, this is too long of a car ride.
When Yelena and Ana are fighting; at 1:05, Ana headbutts Yelena and pushes her backwards toward a set of closed doors. These two doors are composed primarily of glass through which you can see an empty room as Yelena falls backwards. When the camera cuts to inside the empty room at 1:06, the door is now open, and Yelena finishes her fall to roll backwards while throwing Ana to the floor in this room.
Kate Bishops childhood bow is a recurve bow that was strung backwards. The bows are strung backwards when not in use to preserve bow's strength. If they are kept in as they are used, the bows will lose their strength in time. So, that's the correct way of displaying a bow.
Yelena's claim that reindeer meat is tough, and requiring long cooking (which it isn't, quite the contrary) is simply an indication of her apparent tendency to overcook it as a poor cook. In short, she just doesn't know any better, that's the whole joke.
Yelena's strong accent seems a stark contrast to that of her sister, but the reason for this is given in Black Widow (2021) , where she has that same accent.
The green leaves on the trees in New York City when it's supposed to be December.