The smartphone ringtone used in the film is a version of the main theme for Team-up (2016). The phone's owner is played by Myke Hall, who wrote and produced Team-up.
The film-within-a-film that the characters are watching at the cinema is never visible, but audible dialogue and music reveal it is The Turtle Terminator (2017). That film was written and directed by C.J. Lazaretti, editor of Phones Off.