When Mrs. Maisel and Shy are talking on the boat, she's eating a corned beef sandwich (even comments on how lean it is). As the camera cuts back and forth between Mrs. Maisel and Shy, the sandwich disappears.
When Suzie is in the Stage Deli talking with her bookie, the amount of milkshake in his glass changes between camera shots.
Susie uses the phrase "Keep calm and carry on", but the World War II poster that phrase originated on wasn't used in the war and only became famous after the year 2000. it is unlikely she would have known the phrase in the 60s.