The footage of the trapeze act featured in the film (complete with inter-cuts of audience reaction) is identical to that in 'John Moxey''s 'Circus of Fear (1966)'
The song "Look for a Star", used throughout the film during the circus sequences, became a hit pop recording in Great Britain (for Garry Mills) and the United States (for the similarly named Garry Miles). It was written by the young Tony Hatch under his regular pseudonym of Mark Anthony.
Although, at the climax, the circus is known as 'Shuler's Circus' and is clearly labeled as such on exterior shots, the ring is clearly marked round its edge with the repeated initials 'B S'. The 'B S' presumably stands for Billy Smart of Billy Smart's Circus who provided the big top location.
When Shuler is attacked by the gorilla, it clearly shows the gorilla's claw mauling the left side of Shuler's face. Later, only the right side of Shuler's face show any signs of the attack.
Evelyn Morley Finsbury: Evelyn.Morley,is looking at her horribly disfigured face in the bed room mirror that has been caused by Rossiter's bungled plastic surgery she screams and laughs hysterically,"Rossiter!aagh,Rossiter,ha-ha-ha,R-o-s-s-i-t-e-r"