Kay/Lee Soo-Hyun (Lee Joon-gi) takes Seo Ji-woo (Nam Sang-mi) to the race course and they ride horses there in episode 11 of Time Between Dog And Wolf (개와 늑대의 시간) (MBC, 2007).

Also seen in Paradise Ranch (파라다이스 목장) (SBS, 2011); How To Meet a Perfect Neighbor (완벽한 이웃을 만나는 법) (SBS, 2007); Sprint (질주) (KBS2, 1997).

–– Episode 8 of  The Sixth Sense/Six Sense 2 [식스센스2] (tvN, 2021) (featuring actor Kim Sung-cheol)

LetsRun Park Seoul [렛츠런파크서울] or Let’s Run Park Seoul,  which was completed in 1989, is one of South Korea’s main thoroughbred horse racetracks. Renamed from Seoul Race Park in 2014, this is a family park where visitors can experience horse riding, and spend time at the park’s cafés and restaurants. It is located in Gwacheon’s neighborhood Gwacheon [Gwacheon-dong/과천동].

Address
107 Gyeongmagongwon-daero, Gwacheon-si, Gyeonggi-do, South Korea
경기도 과천시 경마공원대로 107
(주암동 685)
Geolocation: 37.4448469, 127.017142

Getting here
Seoul Racecourse Park Station [경마공원역], Seoul Subway Line 4, Exit 2 or 3
You are right in front of the entry.

— submitted by L.C. Lou
— Paradise Ranch; How to Meet a Perfect Neighbor; Sprint added by Marion KDL
— The Sixth Sense S2 added by Mich KDL