Multiple mistakes

[Benchcoach]

HS Game. 1 out R1 on first base. R1 off with the pitch. Batter/Runner hits fly ball to shallow CF. F8 makes apparent diving catch. Ball is seen entering the mitt and out is called by FU. R1 begins retreat to 1b. F8 rises from ground revealing ball underneath his body (apparently ball dislodge from mitt upon contact with the ground and landed under F8). F8 fires to F3 who tags R1 trying to return to 1b. Batter/Runner ceased running to 1b when out called for catch (poor coaching). F3 now in possession of ball retreats to 1b and touches bag. Ruled 8-3 double play. See any problems with ruling?