MediaWiki image title: Image:Nunâ island Upernavik district 2007-08-09 3.jpg
URL "title": Image:Nun%C3%A2_island_Upernavik_district_2007-08-09_3.jpg
If the URL title is used in <gallery> syntax, it gets completely ignored. Not even any text prints out. However using it in a [[:link]] or just normally showing an image [[image:foo.jpg|thumb]] works fine.
This affects images with commas, single and double quotes and parentheses, as well as accented and non-Latin characters such as "â".