Never mind me. I figured it out by myself. Here's the quoted line:
$ ffplay
/media/gga/Datos/movies/trailers/big_buck_bunny_1080p_surround.avi -vf
subtitles=/media/gga/Datos/code/applications/mrViewer/Charlie\\\'s\
Angels.srt:charenc=ISO-8859-1
El 06/09/17 a las 21:36, Gonzalo
$ ffplay
/media/gga/Datos/movies/trailers/big_buck_bunny_1080p_surround.avi -vf
subtitles="Charlie's Angels.srt"
ffplay version N-87016-g7fde655 Copyright (c) 2003-2017 the FFmpeg
developers
built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
configuration: --enable-gpl