According to the MongoDB limits documentation
(http://docs.mongodb.org/manual/reference/limits/#Bulk-Operation-Size)
"A bulk operation can have at most 1000 operations."

However, it appears that this is not correct, as I was able to execute a bulk of over 300,000 operations without issues.

It will be helpful to be clear what (if any) are the limits of bulk operations, beyond the 16 MB BSON size.

Note that I also opened a stackoverflow question regarding that issue and it seems that other also found out the this limit is incorrect.
http://stackoverflow.com/q/24237887/138585