Hints to find
61 items in Blizz World IV
Read this only if you can't find any item for more than 20 minutes
Blue cups with a white stripe
Look next to the trash cans
Visible speakers in the walls
All speakers look the same. Put on your headphones and explore the places on the map where the sounds come from. In some places you cannot see the speakers, so ignore these sounds.

There are 13 speakers in the Warcraft zone.
There are 12 speakers in the Starcraft zone (you need a good speed boost to get two of them). The other two speakers in this zone don't make any sounds.
There are only 3 speakers in the Diablo zone (in front of the castle, including the gate).

Jump on nearby objects to reach some of this speakers
Look at the ceiling
Single round button
This button is small, gray and the only one on the entire map. I mean, the only one you can see. But surely there should be at least one more identical button nearby