German-born Emanuel Gottlieb Leutze grew up in America, then returned to Germany as an adult, where he conceived of the idea for this painting during the Revolutions of 1848. He used American tourists and art students as models and assistants, among them Worthington Whittredge and Andreas Achenbach. Leutze finished the first painting in 1850.

The flag depicted is the original flag of the United States (the "Stars and Stripes"), the design of which did not exist at the time of Washington's crossing. The flag's design was specified in the June 14, 1777, Flag Resolution of the Second Continental Congress, and flew for the first time on September 3, 1777 - well after Washington's crossing in 1776. The historically accurate flag would have been the Grand Union Flag, officially hoisted by Washington himself on January 1, 1776, at Cambridge, Massachusetts, as the standard of the Continental Army and the first national flag.

Artistic concerns motivated further deviations from historical (and physical) accuracy. For example, the boat (of the wrong model) looks too small to carry all occupants and stay afloat, but this emphasizes the struggle of the rowing soldiers. There are phantom light sources besides the upcoming sun, as can be seen on the face of the front rower and shadows on the water, to add depth. The crossing took place in the dead of night, so there ought to have been little natural light, but this would have made for a very different painting.

The river is modeled after the Rhine, where ice tends to form in jagged chunks as pictured, not in broad sheets as is more common on the Delaware. (However, it is speculated that the Delaware River really was frozen over as depicted because of the Little Ice Age that was occurring at the time.) Also, the Delaware at what is now called Washington Crossing is far narrower than the river depicted in the painting. It was also raining during the crossing.

Next, the men did not bring horses or field guns across the river in the boats, but instead had them transported by ferries. Finally, Washington's stance, obviously intended to depict him in a heroic fashion, would have been very hard to maintain in the stormy conditions of the crossing. Considering that he is standing in a rowboat, such a stance would have risked capsizing the boat. However, historian David Hackett Fischer has argued that everyone would have been standing up to avoid the icy water in the bottom of the boat (the actual boats used have higher sides).