In case table name was changed during the mysqldump process taking place, mysqldump would stop with error:
Couldn't execute 'show create table testtable' Table 'testdb.tabletest' doesn't exist (1146)\n")
This could happen if mysqldump was taking a backup of a working slave and during that process table name would get changed. This error happens because mysqldump takes the list of the tables at the beginning of the dump process but the SHOW CREATE TABLE happens just before the table is being dumped.
With this option mysqldump will still show error to stderr, but it will continue to work and dump the rest of the tables.