Creator Backlash: A mild example, compared to others - Stephen Amell has quite happily gone on record with his displeasure over the marketing for season 2... Namely, that the posters highlight the ensemble cast, but leave out Paul Blackthorne & Susanna Thompson.
The Other Darrin/The Other Marty: Following the upgrade of the role of Sara Lance to the Black Canary, they brought in a new actress and started putting her in important scenes, such as the flashback of the shipwreck in the pilot is replayed, only with Caity Lotz playing Sara.
Brady reappears five years after a huge shipwreck that claimed the life of his father and Olivia among others, and becomes a bow-wielding vigilante. He's still hung on his girlfriend Amanda, who's Olivia's sister and is mad at him for multiple reasons, as is her father, Dr. Lawson. His sister is also Marissa's.