Acts 12:10 & 11

"They passed the first and second guards and came to the iron gate leading to the city. It opened for them by itself, and they went through it. When they had walked the length of one street, suddenly the angel left him. Then Peter came to himself and said, 'Now I know without a doubt that the Lord sent his angel and rescued me from Herod's clutches and from everything the Jewish people were anticipating.'" NIV translation

Peter was sort of dazed as they simply walked past the guards. When they came to the gate it just opened by itself as they passed out into the city. After the angel was gone, Peter came around and figured that he couldn't have done this by himself and so came to appreciate what the Lord had done. It seems that we sometimes walk around in a daze not seeing what God is doing in and around us. 

We think that our efforts are so important and many even walk around in a daze not appreciating what Jesus has done for them on the cross. We need to slow down, watch and listen to appreciate God working in our lives.

Acts 12:12

"When this had dawned on him, he went to the house of Mary the mother of John, also called Mark, where many people had gathered and were praying." NIV translation

So, after Peter realized that it wasn't a dream, he went to a house where many of the disciples were gathered and they were praying. The interesting thing here is that they weren't at a fancy building or temple but were simply at a believer's home.

Acts 12:13 - 15

"Peter knocked at the outer entrance, and a servant girl named Rhoda came to answer the door. When she recognized Peter's voice, she was so overjoyed she ran back without opening it and exclaimed, 'Peter is at the door!' 'You're out of your mind,' they told her. When she kept insisting that it was so, they said, 'It must be his angel.'" NIV translation

This is a very strange passage in that, in verse 12, we were told that they had gathered at this house and were praying. But, when God answered the prayer, they did not immediately believe it. We are not told exactly what they were praying but, as we can see, they were not prepared for God's answer. They, as well as us today, should expect our prayers to be answered and not be surprised when God works. Jesus himself encouraged us to pray and to believe that they will be answered.