If you have become lost, stop playing for a little while to see if you can hear where everyone else is. This should not be too difficult if you are familiar with the song and the other musicians are reasonably secure about their own places. If one person is clearly in the wrong place, and everyone else is sure of where that person is, they can attempt to move over to match the out of place performer, but this is difficult to coordinate. Also, it is better to try to correct the person who is out of step than to have everyone be out of step together, because ideally, you want the form to continue uninterrupted. Another thing that can go wrong is an unintended tempo change.
Some people tend to rush, some tend to drag.
Sometimes the interaction between two musicians with good time may cause the tempo to shift. For instance, if a pianist and bassist both play behind the beat, this may make the tempo appear to drag, and the drummer may slow down to not appear ahead of them. If you are convinced the tempo is moving, you may wish to try to conduct a few measures to right the tempo. A metronome can help keep you honest, but playing with a metronome will usually be hopelessly frustrating, because it is virtually impossible to keep a group synchronized with one. For one thing, it is often difficult to hear a metronome when several people are playing.