The Doctor reacts to seeing Craig's flat - "Oh, I see you've redecorated! I don't like it" The Second Doctor said similar lines in The Three Doctors: Episode One (1972) and The Five Doctors (1983), when he saw how his future selves had redesigned the TARDIS.
The Doctor's ability to converse with Alfie came late in development. Steven Moffat came up with the idea for A Good Man Goes to War (2011).
Seven babies and two infant dolls were used to portray Alfie.
The perfume ad that Amy is seen in is for Petrichor perfume. Petricor means the smell of dust after rain. The tagline for the ad is "for the girl who is tired of waiting", The Doctor frequently calls Amy "The girl who waited".
James Corden, who was about to become a father, learned tips from the mothers of the babies playing Alfie.