Katy Perry

Katy Perry

Herself

Shannon Woodward

Lexie Contursi

Lexie Contursi

Himself

Russell Brand

Rachael Markarian

Rachael Markarian

Brandee Evans

Brandee Evans

Herself

Mia Moretti

Himself

Glen Ballard

Johnny Wujek

Johnny Wujek

Adele

Adele

Himself

Adam Marcello

Lady Gaga

Lady Gaga

Himself

Casey Hooper

Rihanna

Rihanna

Himself

Patrick Matera

Himself

Max Hart

Herself

Kesha

Self

Leah Adler

Self

Lockhart Brownlie

Self

Anthony Burrell

Self

Bryan Gaw

Self

Scott Myrick

Self

Cassidy Noblett

Self

Angelica Cob-Baehler

Self

Jason Flom

Self

Jessie J

Self

Justin Bieber

Self (archive footage)

Rebecca Black

Self (archive footage)

Alan Carr

Aaron Christopherson (archive footage)

Darren Criss

Self (archive footage)

Ellen DeGeneres

Self

Whoopi Goldberg

Self (archive footage)

Erica Hill

Self

Lucas Kerr

Self (archive footage)

Heidi Klum

Self

Avril Lavigne

Self

Bonnie McKee

Self (archive footage)

Alanis Morissette

Self (archive footage)

Dermot O'Leary

Self

Britney Spears

Self (archive footage)

Chris Wragge