I knew the Ancestry subscription was rubbish. Sometimes I think they just dont give a damn about their transcripts. 
Only sometimes?
FindMyPast is slightly better, but is still full of errors, mostly geographical, but some of them highly misleading.
There's a family who look to me like Gilhooley in Julia Sweeney's household. SP indexes them as Gilhorley and FindMyPast has Gilhasley.
Can you see a marriage for John and Elizabeth? I had no luck.
No. Sarah's birth certificate should tell us, but on the other hand they might just have invented a wedding. I also checked the English, Welsh and Irish marriage indexes, but they're not there either. But then they wouldn't be if they were Catholic and married before 1864 in Ireland - do we know what religion they were?