After Penny Wootton discloses her age, Jason jokingly suggest Penny must be a Witch. Actress Imelda Staunton, who plays Penny, was famously witch Delores Umbridge in the Harry Potter Franchise.
When going through Jason's closet, Nikki asks how many Ramones t-shirts he owns and says that he doesn't need to dress like their roadie. Rafe Spall (Jason) was in the show Roadies on Showtime, a show centered around a bands road crew.
The odd title refers to the kind of parents are two protagonists should be. Expecting a visit to their flat from an assessor about their child adoption, they decorate their home with what they think the assessor will be looking for. On seeing the perfect room they have for the child, she tells them they are not the type to fill their child's bedroom with craft fair artefacts but are more Barbie Rainbow Castle people - which is fine, as long as they're genuine.