One of my favorite things in this episode was the use of lens flares. There is a reason that the scenes with lens flares were filmed outside on a sunny day that doesn’t really fit the mood of the episode. Lens flares are created by a bright light, especially sunlight, hitting the front of a camera lens and bouncing off different lens elements inside the lens.
You can prevent stray light from hitting the front of the lens by using a hood. Every camera filming outside is going to have a hood. Probably one that adjusts for the field of view and focal length. Here is an example of a camera on the set of Supernatural with a hood.
It would be very difficult to get lens flares on accident with a hood. It can and does happen but if you don’t want them you can make adjustments and reshoot the scene. Higher end
lenses also make lens flares more difficult so when a director wants this effect sometimes a filter is used or a cheep lens.
This particular flare is called a “veiling flare” and it takes place when the source of light is out of frame but the light is still hitting the front of the lens. Some people have suspected that this was added in later. I think there is a natural lens flare here that was edited later to show different colors. But this was originally produced using sunlight. When Sam asks about Cas. Cas shows up as a ray of sun over Deans face. The colors are definitely edited in no one can excuse this as a coincidence like they might excuse Dean’s bi shirt or other props with bi colors. Naturally this flare was probably white-light yellow. Like this.
Someone had to go in later to change the colors to bi flag color. If they wanted just a lens flare they wouldn’t have colored it.
This is another important lens flare that happens during Dean’s prayer. This one looks like it could be completely natural. This could be another sign from tptb that Dean is not straight but I don’t think it is. Dean is talking to God. Talking about how he lost his everything. His whole world you could say. Everyone knows the story of Noah’s ark where God destroys the earth with a flood and makes a rainbow afterwards.
11 I establish my covenant with you: Never again will all life be destroyed by the waters of a flood; never again will there be a flood to destroy the earth.”12 And God said, “This is the sign of the covenant I am making between me and you and every living creature with you, a covenant for all generations to come:13 I have set my rainbow in the clouds, and it will be the sign of the covenant between me and the earth. - Genesis 9: 11-13
I think this could be a promise from God that Dean will not have to go through this again. Dean won’t have to see his everything destroyed ever again. I know that Dean thinks Chuck didn’t answer him but I am wondering if he actually did.