You are not allowed to fill up gaps or provide answers after the specified time is up. It's important to follow the instructions and complete tasks within the given time frame to demonstrate your ability to perform under pressure. You may be disqualified if you attempt to write after the end of given time.

No you don’t get it. If you break the serial, you should confess your blunder during the DP Viva. 

Serial Break

Can’t make constructive and relevant sentence

Lack of originality

Spelling errors

 Taking too long time

Long sentences

Boredom to time management.

The Deputy President's inquiry about your WAT may be a way of expressing interest in your performance. If you  made some errors then he creates an opportunity to confess to him. It could also be related to your interaction with the Deputy President during the assessment process, as they may want to judge your experience and thoughts about the test.