All of our events are restricted to 50 events per call. When there is more than 50 events, there is a next page and previous page URI that you can call to see the next and previous page. You will see that in the XML that is returned when you do the original event GET.
There is a problem currently with the contact collection event calls when calling the next page; however, our engineers are aware of the issue and are working to fix this as soon as possible. Once this has been fixed I will update this thread.
If you have any other questions please let me know.