We found the root cause of the problem and a solution.

There exists a trigger, Schedule_UpdateExpiration, on the ReportServer.Schedule table that references the "TempDB" dbo.ExecutionCache table. We altered the trigger to point to the table with the appropriate fully qualified name.

So far we have yet to notice any other objects that point to the old db name, thus everything is working properly. However, we will keep our fingers crossed.

The thread at the following link was a big help.

http://www.sqlservercentral.com/Forums/Topic553765-147-1.aspx#bm670251