Stuart Bates, 43 and his son Fraser, seven, died after being struck on the A4119 at Talbot Green on 6 December.
The inquest for the pair, from Llanishen in Cardiff, was opened during a hearing in Aberdare.
Coroner Andrew Barkley adjourned the case until 10 March when a pre-inquest review will take place.
The court heard the pair were crossing the road when they were struck by an Alfa Romeo.
Mr Bates was taken to the Royal Glamorgan Hospital, with pathologist Anthony Davidson telling the hearing the cause of death was "multiple blunt injuries".
Fraser was taken to Bristol Children's Hospital, where he died from a "devastating traumatic brain injury".
The driver of the car was arrested on suspicion of causing death by dangerous driving and bailed until 7 February.
On Saturday, mother and wife Anna-Louise Bates described the two as "vivacious and funny" during a balloon launch.
Hundreds of people attended the event, releasing a balloon in their memory.
An inquest into the deaths of a father and son who were hit by a car in Rhondda Cynon Taff has been opened and adjourned.