- The family's real last name is Hanson, but an ancestor thought it was too common and serendipitously changed it to the made-up name of Regbo.
- The age range between his oldest and youngest siblings is 40 years.
- Studied at the Young Blood Theatre Company in London.
- Had second thoughts about his choice of career when, during an acting-class exercise, he was instructed to look into a mirror and pretend he was a plant.
- During his first audition, he was asked why he looked like "he was going to die."
- At 15, he had to do a love scene in Mr. Nobody with Juno Temple's body double, a 34-year-old woman who didn't speak English.
- Portrayed the young Albus Dumbledore in 2010's Harry Potter and the Deathly Hallows, Part 1.
- Had a dialect coach for three weeks of study to perfect his accent for a role as an American teen in 2012's Someday This Pain Will Be Useful to You.