Jim Jim is my name and spanking Rhinos is my game… Ha!!
I think someone in the comments brought up the fact that these tranquilizer darts are exactly fast-acting… This Rhino, for instance, even if Mark was able to get a shot off and place the dart perfectly, would be able to take out an entire village before it was slowed down… So yes, Marlin, you and your Jeep are in a bad spot… Prepare to be launched!!
For pure comic relief check out the effects on Ace Ventura, or for a demonstration of what comes up when one googles “tranquilizing a rhino” see this.