Unity graphic bug ?

Hey guys, sorry but I couldnt find the right question for my problem :/ Do you now how to fix or avoid this problem? You can see it on the screenshots

1. Screenshot: http://fs5.directupload.net/images/160527/vz6go953.png

2. Screenshot: http://fs5.directupload.net/images/160527/yk9okajl.png

If I look from another angular I can see the whole Arrow, And from another one I cant :/