What would you have done?

[Crankin]

The ride leader shouldn't be leading, for 2 reasons. First, it's irresponsible to make a cue sheet like that. Safety is always first. Secondly, it's seems like a very cavalier attitude toward the people on his ride. Granted, if this is the type of ride where people split up into groups and everyone doesn't stay together, this could happen even with a well delineated cue sheet. But at least you would know how to get back.
I would say something to him or the person in charge of scheduling rides...

[snapdragen]

I agree with Robin, definitely let the ride coordinator (or whoever is in charge of scheduling your club's rides) know what happened. It is very irresponsible to assume everyone will "find their way back".