Trailing by Yusif Yakubu's spectacular 61st minute goal, East Bengal made a swift comeback when super sub Ryuji Sueoka fired in two goals in three minutes.
But Armando Colaco's side could not hold on to the lead as some sloppy defence saw the Mumbai side restore parity with a solo effort from Mehta in the 87th minute.
East Bengal now have 28 points from 18 matches, nine behind leaders Bengaluru FC who have played two more matches.
Coming on the back of their win against Rangdajied United FC, the home outfit started with a positive intent and looked to have more possession but the Mumbai outfit gradually found their feet.
Edeh Chidi wasted an opportunity in the 10th minute, while Mumbai FC too wasted opportunities when Shehnaj Singh hit the side net in the first-half.
The hosts had a narrow escape when Alfred Jaryan's shot sailed over the bar before another unlucky second-half strike when he missed an open target, hitting straight to goalkeeper Abhijit Mondal.
Pressed in place of Reisangmi Vashum in the 50th minute, Sueoka unleashed a powerful back volley from inside the box in the 66th minute, and the Japanese gave the lead from a low square pass to inject life into the East Bengal camp.
Just as it looked that the hosts would hold on for a win, an individual piece of brilliance from medio Ashutosh coupled with some shoddy defense by the home side helped Mumbai FC level in the 87th minute.
