I wouldn't recommend leaving missed tubes in, as I found out the hard way that the esophagus can hold more than one inflated ET tube, and it could also push upwards on the trachea
Your best bet would be to pull it out and try a different blade or technique.
Personally I always use a bougie because the bougie will stop when it hits the Carina and if your in the gut it'll keep going all the way down. That way you don't have to find out the rough way that you missed.
If you leave the missed tube in it can spray you in the face with blood like it did me.