Ahh, I saw this happen recently when I positioned ( in a 777) on the flight I was meant to operate ( 744). What happens is that the guys at LHR who provide the stocks of onboard forms, films and safety videos generally provide a package of videos etc based on the scheduled aircraft type ( I know, I know.........), hence ex-LHR we got a video of the 744 procedures and door positions. Fortunately the very sharp Cabin team were on the ball and issued a correcting PA.
BTW QRC well done for noticing, most SLF don't.