Well, I have mixed feelings on whether people should acknowledge things that have influenced their films.
Gene Roddenberry was happy enough to talk about what fed into Star Trek, George Lucas is happy enough to talk about what fed into Star Wars and Raiders etc and a lot of the time the audience is aware of the influences themselves.
Talking about it openly beforehand as one of the possibilities could fend off accusations of 'ripping off' later. Not always, but sometimes getting in first helps!
'If the Apocalypse starts, beep me!' - Buffy Summers
'The sky's the limit.....' Jean-Luc Picard, 'All Good Things'
courtesy of Saquist