Quick question, wouldn't they be able to spot Daniel just by looking?

The trick to recognizing Jewish features is not just finding one feature that seems to match, but you puzzle together what you know about Jews as well as your knowledge of Jewish facial traits, and the more recognizable traits, the stronger the likelihood of being Jewish.

There are different ethnic Jews, so there's some different distinct features that variate. For instance a Jew can have both big ears or they can have small mouse like ears, but bear in mind, a lot of Jews have normal looking ears.
One very recognizable trait on the ones that have it is a chin that is kind of small and that goes in. Here's an example, look at the chin.
http://hugequestions.com/Eric/Neanderthals/Sergey-Brin.jpg

A lot of Jews have kind of narrow eyes which appear somewhat Asiatic. Richard Gere's eyes are a decent example of that. Jews can also have bug eyes that kind of pops out, and also often have bags under their eyes. Then there's the low slanting forehead trait, the big classical hook nose that everybody's obsessed about for some reason that I don't know about, because that's not a good method of recognizing Jews more than the chin or the curly hair. Oh yeah, so curly hair. Jews typical have curly black hair, but other groups of people have that too like Spaniards, Italians, and Africans, but when looking at Hollywood movies, curly black thick hair is one of the better features. Jewish women in Hollywood are often a bit ginger colored, a lot of them dye their hair blonde, but there's also the black haired, and their hair is typically very thick so they make elaborate shorter hairstyles.

Jews have a lot of genetic deficiencies and there are literally hundreds of genetic diseases that are unique to Jews, and most Jews seem to have at least one. A lot of Jews are of a scrawny build, skinny, short, just take a look at Ricky Moranis. There's also a very distinct feature where the lower lip appears big and kind of droopy. Another extremely extinct Jewish feature is a mouth that kind of reminds you of a frog mouth.

Jews can often have lots of thick black curly body hair, bushy black eyebrows and such. If you've seen a person you're not sure if they are Jewish in a movie or something, you can always look up their history. Oftentimes it will say stuff like their father was a economics professor or their mother a traveling salesman or something like that, which are professions known to be favored by Jews. So you use what you know to put the picture together.
Just always keep in mind, on any one individual, you could be wrong. It's hard to be absolutely sure. In Hollywood it's rather easy though since almost every single person on screen, whether an extra or a character, is Jewish.