A complainant contacted Ofcom over the inclusion of sexual material in compilation show 50 Super Epic TV Moments, shown on September 7 on E! at 11am.
Among the clips featured on the show was a scene from Big Brother in 2005 when contestant Kinga Karolczak simulated sex with a wine bottle. The programme labelled the two-minute clip as 'Penis Grigio'.
Other clips included an American TV celebrity undergoing a cervical smear test; a woman on a US talent show smashing soft drink cans with her breasts; a woman apparently masturbating a man underneath a dinner table; and a survival expert performing an enema on himself.
E! acknowledged that the content of the programme was "wholly inappropriate" for the time it was scheduled and noted that the "omission of any warning slates for our viewers only made this worse".
The broadcaster "apologised unreservedly" to viewers and said that its usual compliance processes were not followed in this case due to a period of reorganisation. It has since launched a full review of compliance processes and improved staff training.
Ofcom pointed to its ruling in December 2005 that Channel 4 was wrong in its decision to broadcast the wine bottle scene after it had received 259 complaints from viewers.
The regulator said that the Kinga scene was "highly inappropriate" for children to watch, particularly as it was shown during the morning at a weekend. It said that the other clips shown on 50 Super Epic TV Moments were also inappropriate for broadcast during the daytime.
"Many of the other sequences, including those listed in the Introduction section of this finding, were in Ofcom's view unlikely to be suitable for broadcast at a time when children may be available to view," said Ofcom.
"Further, the cumulative effect of the numerous clips made this programme in general unsuitable for transmission before the watershed in Ofcom‟s view.
"Ofcom acknowledges the Licensee's apologies in this case and its intention to improve its compliance arrangements. Nonetheless, these were clear and serious breaches of the Code and Ofcom does not expect any similar compliance failures by E! Entertainment in future."
Last month, E4's Canadian drama Being Erica was censured by Ofcom for showing an ice sculpture shaped like a penis at a time when children could have been watching.