Becky is played by Teresa Palmer, an Australian. Averted with Peyton Roi List, who is American.
Jay Baruchel is Canadian. Averted with Jake Cherry, who is American.
Shown Their Work: As revealed in the behind-the-scenes material, the place where Dave has his secret lab (which is then turned into his apprentice training ground with Balthasar) is an old subway turnaround, and based explicitly (in architecture and design) on the City Hall IRT station.
The same earlier draft included Abigail in the climactic battle, as well as more emphasis on how magic works, different backgrounds for Balthazar and Horvath, and the title of Prime Merlinian being generational rather than once-in-a-lifetime.