starting the db in mount state
This method is not correct. These are the four steps for incomplete recovery (which is what you need):
mount the database
restore all datafiles
recover database until....
alter database open resetlogs
Your DBA (who you say was responsible for the error) will be familiar with the routine. Or he should be.
If you have doubts about the procedure to use to restore a backup to a point in time, then please take a look at the documentation first: Performing Flashback and Database Point-in-Time Recovery - 11g Release 2 (11.2)
After you specify the time when the recovery must end (UNTIL clause in rman), then the RECOVER command will try to use the archivelogs needed.
Before starting with this PITR operation, you should check if your database has flashback active, because it will be much easier to recover using it.
This is also explained on the same document linked above.
Hope ur performing those operations while cloning the database
you should use (set until time ) option to recover controlfile from backup (time being the time of table drop)
then restore this database , take expdp backup of the table and import it in production
Make sure their all the jobs running against that table are disabled ( insert update delete)