If it's a data error, it's on Twitter's part. We trust the geolocation of their data. However, Indonesia is always bulging. It wouldn't need many global tweets to be large in relation to it's area.

As I said in a previous comment, I've observed this seemingly-out-of-proportion presence of Indonesia on twitter before, since quite a long time. This map confirms those observations. Russia however... ;-)

Indonesia does have the fourth largest population of any nation in the world... could that explain it?

I wonder what public evidence of Twitter looks like besides people playing with their phones.