During EDL - the heatsheild was ejected first - not long after deploying the parachute. So as the spacecraft was quite high at that point - and still travelling quite fast - the heatshield essentially went further down range that the rest of the spacecraft (i.e. east in case of both rovers)

The backshell - and attached parachute stay with the spacecraft right to the moment of firing the retro rockets at which point - the ball of airbags, rover included, is cut off from a bridle swinging below the parachute and backshell.

So - for each rover - there were three elements that made it to the ground. Lander, heatsheild, and backshell with parachute.

In the case of opportunity - the backshell and parachute were spied quite early on - a couple of hundred meters south of the crater - and then the heatshield was spotted way out near Endurance crater.

With spirit - the heatshield impacted the side of Bonneville crater - and was seen up close, and infact imaged using super-resolution techniques that Tim Parker tried with Pathfinder back in '97 - the results of which never made it out of JPL - but I had a go myself

The backshell and chute ended up way north of the lander - and were spotted part of the way up the flank of Bonneville crater -

(39 odd meg) - that panorama is the only one for Spirit in which you can see Lander, Heatshield and Backshell/Chute

The same is true of the Lion King panorama from Opportunity.