Last tested: Dec 31, 2019
1. Filename: it is case sensitive, however, we rarely have any impact since we don't reference the file name in the lookml.
2. View name, dashboard name and field name: it is case sensitive, and we will have to ensure we reference the view, dashboard and fields with the correct case.
3. Filter value: By default Looker filter UI is case sensitive, this also depends on the sql dialect and the settings in Looker, and it can be case sensitive. There's a parameter for it: https://docs.looker.com/reference/model-params/case_sensitive-for-model
4. Referencing lookml field in Liquid: this is also case sensitive.