Trivia

For her role as Joanna (Sam's crush) in Love Actually (2003), she does all of her own singing in "All I Want for Christmas Is You" at the Christmas concert. She had such an amazing voice that writer and director Richard Curtis had it edited so it sounded more like a child singing.

Her character, Joanna, in Love Actually (2003) is the love interest of Thomas Brodie-Sangster's character, Sam. She also voices the character of Vanessa in the television series Phineas and Ferb (2007), in which Thomas Brodie-Sangster's character, Ferb, is romantically interested in her.

Olivia also sings the song "Haven't You Noticed (I'm a Star)" in the American kids' show Steven Universe (2013) in the episode Sadie's Song (2015) and in the short Steven Universe: Gem Karaoke (2016).