Ashton, Lewis Moody, Steve Thompson, Danny Care and Jonny Wilkinson were among a number of current England stars invited to Saturday's royal wedding.
Reports have stated that the party in Edinburgh continued into Sunday.
England manager Martin Johnson, who has cut his squad down to 40 players ahead of back-to-back World Cup warm-up games against Wales, put his men through a rigorous fitness test.
"They normally give us (fitness) programmes through the weekend but they didn't last weekend because they knew a few of us would be going up to the wedding and having a drink," said Ashton.
"It gave people a bit of a chance to relax knowing that we were going to go hard this morning in fitness tests and I think they have managed to get us back if we had a drink this weekend!"
Asked whether any of the England players were sick during the test, overseen by national fitness coach Calvin Morris, Ashton joked: "No one ate breakfast!"
Tindall was given an extra night away from camp but returned to Pennyhill Park today and was training with the squad this afternoon.
"Mike went up Thursday lunchtime and he is back now - he probably feels like he has never been away," said Johnson, who was also one of the guests.
"He looked fine. Anyone who is fit is in the reckoning to play at the weekend. We will announce the squad on Thursday."
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