Hey there, Jonas!
Joseph is absolutely correct–the location search uses the Google Maps API and having it included twice on the same page can cause conflicts in its functionality. Looking at the site, it looks like the API is indeed included twice on the page.
This can sometimes be solved by changing your calendar settings (Events > Settings > Display) to use the default calendar template instead of a theme template.
If that doesn’t work, however, then hunting down source of the second instance (as Joseph suggests) and disabling it is the best route to take.
Does this make sense and help you get started? Please let me know. 🙂
Geoff