Running more accurately with my RS200sd

Today, I survived a really dry series of induction courses at work. Thankfully, after that, I was able to go for a run at 7:15 pm. I took the same route around my workplace which I had run with Yeen Teck last week (Loewen Rd - Nassim Road - Botanical Gardens - Minden Road), and to my surprise, my footpod registered about 7.7 km (including a few extra wrong turns, because this was the first time I was running the route in the dark on my own). This was much more than what I had measured off my street directory (which goes to show how inaccurate measurements from maps are...). Just to be sure, I ran the route a second time, and I confirmed that the distance was 7.3 km. In total, I did a good 15 km.

My stats:

Lap 1 (Office Gym to Loewen Rd until Nassim Rd ~ 3.89 km)
Time taken: 22 min 24 sec
Maximum/Average Heart Rate: 173/150
Average Pace: 5 min 45 sec

Lap 2 (Nassim until Botanical Gardens ~ 1.59 km)
Time taken: 8 min 11 sec
Maximum/Average Heart Rate: 184/177
Average Pace: 5 min 08 sec

Lap 3 (Through Botanical Gardens - Minden - Office Gym ~ 2.28 km)
Time taken: 12 min 33 sec
Maximum/Average Heart Rate: 215/181
Average Pace: 5 min 30 sec

Lap 4 (Whole Route again ~ 7.24 km)
Time taken: 40 min 9 sec
Maximum/Average Heart Rate: 222/186
Average Pace: 5 min 32 sec

Total (15 km)
Time taken: 12 min 33 sec
Maximum/Average Heart Rate: 222/175
Maximum/Average Pace: 4 min 39 sec / 5 min 33 sec
Calories Expended: 1047 kcal