When Penelope is speaking with her mother trying to convince her to let her continue her studies for another year she is seen holding a book. When she walks away she no longer has a book in her hands.
When Dapne returns from her debut, Lady Whistledown's newsletter has already been printed and delivered.
During the presentation to the queen, Daphne's mother is announced as "the dowager Viscountess Bridgerton." Although her eldest son has inherited the title, until he is married his mother is not called "dowager." That adjective would only be used to distinguish her from a daughter-in-law holding the same title.
While on their horse ride in the park, Lord Anthony & Miss Daphne Bridgerton, are talking and Miss Bridgerton's blue veil on her hat flies up above the brim in a breeze. The next scene it is back over her face.
At the ball, many young ladies seeking husbands are wearing tiaras. UK etiquette has always been clear that tiaras are for brides on their wedding day and married women only.
In the first scene, the modern double yellow "no parking" lines are visible on the road next to the carriage.
There are yellow lines indicating no waiting on the road, which weren't introduced until the 1960s.