Allein unter Schwestern

The movie title is a pun that can be interpreted in more than one way. At the start of the movie, Kos' dad is changing the name sign of the hotel, and due to an errand he doesn't complete the installment of all letters, so the hotel appears to be named "Hotel De Grote L" (meaning "The Big L Hotel"). One pun is that the letter L could stand for a (possibly obscene) Dutch word that starts with the letter L. Eventually, Kos' dad finishes the lettering and the hotel is named "Hotel De Grote Liefde" (= "Hotel The Big Love"), referring to the hotel as being a project of passion that the dad once started with his now deceased wife.

Another possible pun is that the movie title can also be read phonetically as "Hotel de grotel". This sounds similar to the Dutch word "Hoteldebotel", which is a slang word that means "Madly in love". This ties in with one of the main themes of the movie (as Kos is madly in love with Isabel and doesn't know how to deal with it).

(at around 58 mins) During his second visit to the hotel, Mr. Gans picks up a guitar that's leaning against the wall and calls it "a nice Fender Stratocaster", but it's actually a Telecaster model.