what everyone here has failed to mention is your van has a redline limiter so it may have just glazed the surface of the redline mark but it will either shift or choke down the motor before it actually red lines. also the car is 10yrs old probably nearing 150K. and not knowing maintenance history the car is getting older and sure it will make sounds or hesitate now and then. Before you go blaming your friend here when was the last time you changed the oil or spark plugs even with the iridium plugs they are only good for around 80K maybe the air filter?

Of course it hurts your engine, a little engine life every time you redline the engine. If you keep your engine over redline to long could cause the engine to fail outright. So yeah.

Impossible to diagnose here - - but if as you say the vehicle no longer runs as smoothly immediately after the fool hot-rodded it, obviously something WAS damaged. Did the idiot think your mini-van was a race car? Suggest he buy if from you for what it was worth before he trashed it - then HE can sort-out what he did.

Reving past the red line will shorten the engine life considerably. You can damage interal parts.

Valvetrain damage can cause noise, or you may have damaged a bearing, which could lead to total engine destruction. Good friend you have

My friend was driving my car on a trip and 2 or 3 times revved the engine past the redline while accelerating onto the highway. It was only in the red for a couple seconds each time. Now I notice a rattling or grumbling sound in the engine when accelerating. The engine seems to run more or less OK, but not as smoothly as before.

Could revving it past the redline like this have caused any damage to the engine?

Any info would be appreciated. Thanks.