Don't panic. It looks like Toyota red coolant dripping from rear weep hole. You did used "red" didn't you! Since you had a leak at engine side of upper radiator hose. I'll bet it flooded the engine valley, by flowing over the top of water pump and front of engine. Then, drained out the back drains of valley under the stater. If ATF that will have a very nasty smell, coolant will be sweet.
Why you blew the radiator. Well the tops go bad and weaken then weep. Look back at picture
@flintknapper posted where top of radiator is blown off. Then look at that cap and the hose in the reservoir. Notice anything. The cap is old and corroded and hose cruddy. If radiator cap becomes stuck, not releasing fluid at 15PSI to reservoir, pressure keeps builds within the coolant system. Something must give. That's weakest point.
I've replace 5 radiators in last year. Three the tops where crumbling. Non blew. Why? Cap were working.
When I replace Radiator I also swap all form to new one. If using OEM they come with new foam, but for the saving I'll swap and glue. I also replace cap, thermostat and both upper and lower hoses.
But if for some reason I've reused any hose. I always place back in same spot and always put factory clamp in same spot. The clamps leave marks on the old hose making it easy.
Did you damage heads or heads gaskets.
Not likely form Just from this. It generally longer term where the coolant was not detected leaking and drop below water sending unit. Temp gauge reads cool when this happens, because sensor is reading air rather than fluid temp. Then driver just keeps driving thinking all is okay, and really heating it up. I've seen knock sensor, cam sensor and intake manifold melt (VVT engine) when this happen. Hose in engine compartment turn brown. Oil turn to milkshake as coolant mixes in.. (see
Unicorn)
