Unfortunately, there were a number of priests at the time who were doing a variety of things with young boys that they should not have been doing.
I would imagine even those priests who transgressed privately tried to avoid the appearance of scandal in public, not to mention the fact that society had yet to be fully debased; I doubt Americans in 1972 would be so understanding seeing a priest taking young chilredn to an R-rated movie.
After the priest died, and the pedophile priest stories broke, we learned of one trip the priest was adamant my cousin could not go on. The cousin was angry at the time. The place was a NYC pool (NY Athletic Club? IIRC) where the priests and boys would swim naked. It still angers me that this future monsignor knew what went on yet did and said nothing. Probably to cover up his drunken, girl friend screwing ways and to get his promotion. He knew - so many knew - and did nothing but protect the pedophiles.
So, yes, Tim Robbins could have gone on field trips with priests.