The keeper was still behind his goal, adjusting his net when the Hammers kicked off.
Henri Lansbury noticed Forde was not paying attention and sent a 40-yard shot bouncing narrowly wide as the keeper sheepishly jogged back into position.
"It was a bizarre incident," admitted Lions manager Kenny Jackett.
"He wasn't happy with the referee and I'm looking forward to seeing it again.
"It looked exactly like he hadn't seen the game had kicked off, but I haven't spoken to him yet."
Allardyce added: "I thought it was a fantastic piece of vision by Lansbury - I hadn't got a clue and was thinking 'why the hell are you shooting there?'
"But he'd obviously seen the keeper and the position he was in, and if the ball had been on target it would have gone in the back of the net.
"It would be nice to be talking about it for a long time if it had gone in, but unfortunately it didn't."
"Henri Lansbury had the best chance in the first half, Kevin Nolan had a chance we'd expect him to score, if he'd chested it down and slotted it in instead, and Bentley had an unbelievable chance but he put it wide," added Allardyce.
"In the end we are disappointed we didn't win it but we are happy and respect the point that we've got."
"I'm not disappointed with a draw," added Jackett. "West Ham are very strong, they have a very good side so I'm pleased.
"We defended well and we are competitive but now we have to find our way going forward and get some goals."